Noticed that the previous guide was rather outdated, so I decided to write a new one!

Note: All things were tested in terraria 1.4.4.9 with Elaina version 2.1.5. Furthermore, cheat sheet and journey mode was used for testing in this mod, and it was sideloaded with Calamity. It is unknown if the mod rebalances around Calamity. I was too lazy to decompile and check and also too lazy to unload the mods I'm using in multiplayer atm, will retest in the future.

All tests were done on a target dummy in Master Mode + Calamity. Numbers may vary.

Your character must be named "Elaina" or "伊蕾娜". These characters can be freely renamed after the fact. You can confirm it's correct by seeing Elaina as a custom character sprite. You will spawn into the game with 1 wand, 2 "Elaina Hat", 1 book, and one "The Adventure's of Nikah". For the readability of the guide, Elaina will refer to a character that was created with one of the two aforementioned names.

Playing as Elaina will give the following effects.

• HP increases are half as effective (Max 200 with life crystal, 250 with life fruit in vanilla). The amount of hp increase items required to reach this cap is unchanged (15/20 for crystal/fruit).
  
• Mana potions are automatically used (same as mana flower), and no longer grant the mana sickness effect.
  
• Mana regeneration is vastly increased
  
• Picking up money "Happy" buff, with buff description "Got Money, Happy! speeding up the recovery interval (Unconfirmed, Not sure what it does, based off mod description) and briefly granting 20 mana and max mana upon obtaining the buff.

The mod's progression is based off a proficiency system. Your proficiency starts at 0, and increases by 1 based off the world's progression of vanilla bosses. This can only ever increase and not decrease. This means if you ever enter a world with a higher progression than your own accidently, your Elaina will "level up" to that world's progression, and such a level up will transfer over to other worlds. The proficiency increases as follows:

0. Starting off
1. Eye of Cithulu
2. Brain of Cithulu/Eater of Worlds
3. Skeletron
4. Wall of Flesh
5. First mech boss
6. 3 mech bosses defeated
7. Plantera
8. Golem
9. After defeating all 4 lunar pillars
10. Moon Lord

Note that all items in this mod must be crafted by Elaina. The items will be in the format:
Name - Recipe - Description of effects

The items are as follows:

• Wand - 1 wood - The basic weapon used to cast all spells from Elaina. Non-Elaina players will see it as a stick.
  
• Broom - 10 wood, 20 hay, workbench - A flying rideable mount.
  
• The Adventures of Nikah - Uncraftable, Spawns on character creation - See details below
  
• Cauldron - 10 any iron bars, 1 campfire - Used for Alchemy (see Alchemy section)
  
• Spell tome - 1 book, 10 fallen stars - Same as a vanilla spell tome, but can be obtained pre-hm due to crafting recipe.
  
• Spell books - See Spells section; Only cartable if not learned- Learn the Fire/Ice/Wind/Healing Magic.
  
• Magic Sharing Ring - 10 hallowed bars, 1 mana regeneration band - max mana +20, mana use -20%, mana is shared between players wearing the ring
  
• White Dolphin Necklace - Cross Necklace, Avenger Emblem, 150 Nebula Fragment - 10% increased magic damage, Upon a fatal hit, will prevent death once and full heal (3 min cd, unconfirmed in game tooltip).

The Adventures of Nikah:
A book whose tooltip grows with every boss you kill. Bosses are all things labeled as boss by the game/mod authors (I know, very descriptive). Works on modded bosses, ignores most mini bosses (again, depends on the mod). Each boss you kill will increase your damage done to bosses by 1%. Note that it must be equiped in your accessory slot at the time of the boss death to count, which is really only relevant in mediumcore as you will have this permanently equipped otherwise.

Alchemy requires a cauldron. Start by placing a cauldron on the ground and right clicking it to enter a refining phase. The top right has a "?" which you can see for complete recipes. Place the ingredients in the matching colored background. Right click the cauldron to begin crafting. Right click the air to escape crafting. If the cauldron glows red, an invalid recipe is used and it will blow up shortly in a small radius, destroying all items inside and dealing roughly 200 damage. The recipes are as follows

• Duplication - See Below
  
• Ultimate Mana Potion - Lesser mana potion + 3x dirt/clay/stone/mud block - restores 1000 mana and sells for 2 gold (roughly, untested with neutral happiness).
  
• Water Power Potion - Magic Power Potion + 10 Fallen Stars + 10 Coral - 20% increased water damage, lasts 4 mins
  
• Flame Power Potion - Magic Power Potion + 10 Fallen Stars + 10 Fireblossom - 20% increased fire damage, lasts 4 mins
  
• Ice Power Potion - Magic Power Potion + 10 Fallen Stars + 10 Shiverthorn - 20% increased ice damage, lasts 4 mins
  
• Lighting Power Potion - Water + Flame + Ice power potion - 20% increased lightning damage, increase lightning frequency, lasts 4 mins
  
• Critter potion - Gender Change Potion + 10 fallen stars - Consumable thrown potion which explodes on impact, turning all nearby players into a random critter. Fun little prank and mildly useful (early flight)

DUPLICATION
The main use of alchemy, use it to duplicate items. Note that testing is not complete because it's too expansive to test properly. Most of the duplication info is from "DatGuyBoopy's" original guide. Credit goes to him.

Anything labeled "material" in the tooltip can be duplicated. To duplicate, place the item you want to duplicate in the center and obsidian in the left or right. The amount of obsidian dictates how much of the item you will craft. The ratio of item:obsidian varies with the rarity of the item and as your proficiency increases. The rarity of the item you can duplicate is based off your current proficiency level. Duplication uses very little mana after prof 4, although it is always useful to have extra mana potions on hand. They are as follows:

• 0/1 - Gray/White
  
• 2 - Blue
  
• 3 - Green
  
• 4 - Orange
  
• 5 - Light Red
  
• 6 - Pink
  
• 7 - Light Purple
  
• 8 - Lime
  
• 9 - Yellow
  
• 10 - Cyan

As your proficiency level increases, the following also changes for lower previous rarities:

• Speed of duplication
  
• Better ratio of duplication
  
• Reduced Mana cost

You can also seem to duplicate slightly above your level, at a reduced ratio of item/obsidian, and a lot of extra explosions. The primary use of duplication is for those expensive potions and spellbooks. Note that all damage is without any equipment on a target dummy.

Spells are your main source of damage as Elania. There is a total of 9 spells you can access, all of which are cast with your wand. To change the spell, press the "Q" hotkey to open up a spell selection circle. Spells are unlocked via spellbooks, which are either crafted or obtained in the world. Most spells have breakpoints in which they level up, which will be indicated by the bold levels. Most spells also have differing behavior between a tap and a hold. Note that all spells are cast in front of Elania, and thus can "pierce" the first few blocks. Note that some spells can not be obtained naturally at certain progression levels.

Disclaimer: Damage values area guess of the base damage for each spell. Note that all spells have some random variance in damage. Spells with damage range are a guess of where the base damage is due to having higher variance, not the upper and lower bounds.

Other Notes:
Proficiency also effects the broomstick speed, and mana regen speed. Mana values are not given after level 3 due to high mana regen making it both irrelevant or hard to measure. Mana costs don't appear to change anyways for the ones that can be measured. Brooms may be measured and added at a later day

Light
Unlocked by default.
Classic Light spell. Middle click to toggle, lighting up an area brighter and larger than a white holding a white torch. No noticeable changes with proficiency.

Magic Barrier
Unlocked by default.
Right click to cast. While the barrier is active, it reduces the damage you take significantly and consumes mana. No noticeable changes with proficiency . Damage is reduced close to 1, but multiple later calamity bosses seem to do more damage.

• Level 10 - Magic barrier is automatically cast on hit by a projectile.

Flight Magic
Use your broom (equip and use as mount) to fly! Flying costs mana. Mana use decreases with proficiency for reqular flight. Press space to get a boost, hold space to fly at higher speeds, both using increased mana. Flight speed and boost speed increases with proficiency . Will be measured at later date (maybe).

Magic Missle
Unlocked by default.
This is your first offensive spell, shooting a purple missle in a straight line. The missle will pierce through terrain within 19 blocks of it's casting origin, and will collide on the 20th block and onward.

• Level 0 - 5 mana / 20 damage. Tapping shoots more frequently than holding.
  
• Level 1 - 5 mana / 20 damage.
  
• Level 2 - 5 mana / 22 damage.
  
• Level 3 - 5 mana / 28 damage. Tap: 15 mana / 28 damage per missile. Magic missiles have a weak homing property. Tapping now summons 5 magic missiles in quick succession. These will home onto nearby enemies. This can not be cast again until the right most missile slot (first missile) is fired off. Rapidly tapping when bosses are nearby will as a result constantly spawn 5 missiles at a time.
  
• Level 4 - 34 damage.
  
• Level 5 - 43 damage.
  
• Level 6 - 52 damage.
  
• Level 7 - 62 damage.
  
• Level 8 - 75 damage / missile. Hold: 2200-2600 dps. Hold now shoots a constant stream of missiles with insane mana consumption. (note missile damage is unreliable since you can no longer test on target dummy)
  
• Level 9 - 90 damage / missile. Hold: 3000 dps.
  
• Level 10 - 110 damage / missile. Hold: 3600 dps.

Water Magic
Obtained by breaking books in the dungeon. Drop rate of book is increased during rain. Can be cheesed by entering the dungeon, and breaking and replacing books until it drops. Will not drop for an individual Elania after the magic is learned.

Your first real damaging spell made out of water. Unless disabled in config, the hold attack will generate water in the world. (Highly reccomend disabling in multiplayer at minimum)
Tap - Spawns a little drizzle on your cursor, giving them the wet condition.
Hold - Form a water ball, which can be released for damage. Any unused water will be spawned into the world. Water can be absorbed from rain, drizzle, and water sources. When using water from water sources, it will consume some water to cast the spell. Casts roughly 3 blocks in front of Elania.

Only hold does damage.

• Level 0 - 15+3 mana / 135-145 damage. Absorbing water eliminates the additional mana cost requirement.
  
• Level 1 - 15+3 mana / 135-145 damage.
  
• Level 2 - 15+3 mana / 135-145 damage. Occasionally does 170+ damage instead.
  
• Level 3 - 110 (uncharged)/220 (full charged) damage. Holding now charges up multiple (4?) times, doing increasing damage for each charge. Each charge takes an additional bit of mana. Having water present will instantly max the charge and not use any mana.
  
• Level 4 - 110 (uncharged)/340 (full charged) damage.
  
• Level 5 - 110 (uncharged)/405-415 (full charged) damage. Extra charge level, water ball is bigger.
  
• Level 6 - 110 (uncharged)/520-540 (full charged) damage.
  
• Level 7 - 110 (uncharged)/1300-1400 (full charged) damage. Extra charge level, water ball size increases dramatically, will have one orbiting ball of water around main ball at max charge. Doing a full charge by absorbing water gives you an orbiting ball of water around Elaina. Each orbiting ball reduces damage taken by 10%. New sound effect for large ball
  
• Level 8 - 110 (uncharged)/1600-1800 (full charged) damage.
  
• Level 9 - 110 (uncharged)/2180 (full charged) damage. A second orbiting ball now forms.
  
• Level 10 - 110 (uncharged)/2500-2700 (full charged) damage. A third orbiting ball now forms.

Healing Magic
Crafted with a spell tome, 50 vines, 50 jungle spores, and 50 moonglow.

Tap - no noticeable effect
Hold - Heals and cleanses (removes negative debuffs) you and nearby players. Once channel begins, players can leave the range and still recieve the heal.

• Level 0 to 10 - 11 mana/s / 20hps. Might heal faster starting at 3? Could be Placebo. Need video data to verify

Fire Magic
Crafted with a spell tome, 15 hell butterflies, 50 fire blossom, and 50 hellstone.
Become the firebender you were meant to be.
Tap - Shoots a large fireball. Fireball can explode and destroy terrain. Toggle with a hotkey (default "*", defaulted as unbound). Casts roughly 12 blocks in front of Elania. Fireball instantly explodes on contact with water. Applies fire onto enemy.
Hold - Shoot a deadly beam of fire, perfect for impersonating Fire Lord Ozai. Lights trees on fire, chopping them after the fire burns for roughly 5 seconds. Fire can be extinquished by water and rain. Has no effect on all other blocks. Evaporates water and destroys it, useful for emptying a lake! Casting will be canceled if blocks are too close in front of the wand. Applies fire onto enemy.

Damage onto wet enemies will deal evaporation damage, doubling the damage taken. Rain ironically will drastically increase the damage as a result.

• Level 0 - Tap 50 mana / 85 damage. Hold: 30 mana/s / 90dps.
  
• Level 1 - Tap 50 mana / 105 damage. Hold: 30 mana/s / 100dps.
  
• Level 2 - Tap 50 mana / 160-170 damage. Hold: 30 mana/s / 170dps.
  
• Level 3 - 270 damage. Hold: 280 dps. Massive increase in damage.
  
• Level 4 - 400 damage. Hold 460 dps.
  
• Level 5 - 570 damage. Hold 580 dps.
  
• Level 6 - 820 damage. Hold 830 dps.
  
• Level 7 - 1150 damage. Hold 1100 dps.
  
• Level 8 - 1400 damage. Hold 1350 dps.
  
• Level 9 - 1700 damage. Hold 1800 dps.
  
• Level 10 - 2000 damage. Hold 2400 dps. Fireball can now be shot rapidly.

Continued in comments, too long for one post

Edit: Title and formatting
Edit 2: Orbiting water ball mechanics