A few advanced tid bits and tips I've learned

[DeepwellBridge]

Learn when to move and when to stand still. A minimal amount of movement is more effective then freaking out and jumping all over the place (this is especially helpful during the harder sections and or the later game + sections). If you have to move make it count.

Instead of upgrading your health at the start, upgrade your defenses so that you take less damage. This will allow your vampire runes and armor to be more helpful for a longer period of time. This only works at the first and maybe the Game +1.

Eventually you will have to get rid of all vampiric items/runes during the G+. Replace the runes with something that helps you dodge better. I go with two haste runes, a dash rune, a fly run, and a jump rune. Later on this will change with the black armor (no spoilers here).

UPGRADE YOUR CRITS!!!!

Classes you can ignore during G +.
Lich and Lich King (he's okay at the beginning but too weak later on)
Dragon (He only shoots left and right leaving him vulnerable above and below)
Miner/Spelunker (you get more gold by surviving and killing, minor's die too quickly)
Shinobi/Hokage (good at the start of the game horrible later on once you upgrade crits)
Mage/archmage (good at the start of the game too weak in game + games)

Classes that are awesome (in order of awesomeness)!
Spellthief/SpellSword (best magic user in the game, the SpellSword can do a mega spell that does twice damage, think of it as a guaranteed magic crit.)
Knave/assassin (this class is okay at the beginning but has great uses towards the later part of the game. He can assassinate him some bosses.)
Knight/Paladin (all around good guy. I keep forgetting he has a shield... but heck its there if I need it.)
Barbarian/Barbarian King (has a lot of hp... this is always a good thing)

I usualy choose throwing spells that can go through walls like the axe or the sickles. If this isn't possible then I use something I can throw like a knife.

Best spells to take in a boss fights.
Khidra the big eye boss (the sword)
Alexander the Forgotten (spike balls is optimal do NOT ever use the knife if you can help it.)
Ponce de Leon the flaming ball with eyes (the sword or shuriken)
Herodotus the large blob (I found shuriken to be most effective, shoot a bunch of them towards the edge of the screen and let them cut through the whole screen. Spike balls might also be a good bet here.)

Final boss (no spoilers here)
The best combo is a spell thief with fire, you can turn on the heat and hit him for a continuous ball of fire all the will refurbishing your magic. It basically breaks the game!
Sword, axe, and shuriken are also useful.

[Pixel Peeper]

I'd say that's pretty accurate.

Some thoughts:

The Half-Dragon may be pretty bad against trash mobs, but it's actually a fantastic boss-killer that can deal with the 2nd, 3rd and 4th bosses insanely easily. It can get many types of fairy chests easily too.

The Barbarian King isn't just good because it has lots of Health; it can also Shout projectiles right off the screen, very valuable in NG+2 and above.

I think the Flame Shield spell or whatever it's called is the best spell overall, with the Chakram second. Dagger's also very good for the final boss.

[DeepwellBridge]

I always forget about that skyrim yell! Good thoughts on the Half-dragon.

[Refrag]

Ignoring the Lich King/Queen class? Hell no, best class in the game if you know how to use it properly. Especially when equipped with Dark Armor.

Best combination is the lich king/queen with the Crow Storm spell. With this class i managed to get to +4 and have runs netting between 200k-300k gold. It's the best class+spell combo when fighting Herodotus and Alexander , the crows will destroy Herodotus with absolute ease.

It's amazing when you enter a big room and cast crow twice, cleaning the entire room as each crow does a ton of damage. And each time you kill you get a permanent +4hp (up untill you hit a cap) and also +10hp and +10mana due to Armor.

Lich King/Queen truly beats any other class in this game if you ask me.

[Pixel Peeper]

Crows is a pretty good spell, but if you're going the Magic route, why not just use a Spellsword with Flame or Chakram? You'll do 33% more spell damage than a Lich King would do, continually, and have infinite mana.

I have no idea what you mean about +10 HP and +10 MP due to Armor. Armor only reduces damage taken by a %, it does nothing else. Is there something I'm missing?

[Mano]

lich with crows
Archmage with time stop.
Just saying ;p
Also I will disagree about upgrading armor. (I believe someone actually did the math that hp was better than armor for a long time)
but also turkey/chicken will give more hp back.

[DeepwellBridge]

Good ideas on here! Things I've never tried or thought of before.

I'm going to try the Lich King/Queen with the crows! That honestly sound badass. I guess he's worthless with any other spell though.

[Sensei Le Roof]

Originally posted by Tripoteur Ventripotent:

Crows is a pretty good spell, but if you're going the Magic route, why not just use a Spellsword with Flame or Chakram? You'll do 33% more spell damage than a Lich King would do, continually, and have infinite mana.

Crow Storm moves in all directions (bye-bye, Chakram).
Crow Storm has full-room range (eat it, Flame Wheel).
Crow Storm is homing (so much for Every Other Spell in the Game).
Its only limitations are being the most expensive spell (but that's what cost reductions are for) and only eight targets per casting (O NOES!).

Originally posted by Tripoteur Ventripotent:

I have no idea what you mean about +10 HP and +10 MP due to Armor. Armor only reduces damage taken by a %, it does nothing else. Is there something I'm missing?

I think he's referring to the final armor set, which provides +5 Vampirism, +5 Siphon, +2 Air Jump, +3 Air Dash, +5 Retribution (I think), and possibly something I'm forgetting. Like its name.

[Pixel Peeper]

Originally posted by Sensei Le Roof:

Originally posted by Tripoteur Ventripotent:

Crows is a pretty good spell, but if you're going the Magic route, why not just use a Spellsword with Flame or Chakram? You'll do 33% more spell damage than a Lich King would do, continually, and have infinite mana.

Crow Storm moves in all directions (bye-bye, Chakram).
Crow Storm has full-room range (eat it, Flame Wheel).
Crow Storm is homing (so much for Every Other Spell in the Game).
Its only limitations are being the most expensive spell (but that's what cost reductions are for) and only eight targets per casting (O NOES!).

Originally posted by Tripoteur Ventripotent:

I have no idea what you mean about +10 HP and +10 MP due to Armor. Armor only reduces damage taken by a %, it does nothing else. Is there something I'm missing?

I think he's referring to the final armor set, which provides +5 Vampirism, +5 Siphon, +2 Air Jump, +3 Air Dash, +5 Retribution (I think), and possibly something I'm forgetting. Like its name.

Ah, but the Crows only hit once per casting, don't they? The Chakram will often hit 3 times per cast. At 33% more damage per cast that's four times as much damage, for much less Mana (which isn't even an issue if you're a Spellsword).

You're probably right about the gear giving +5 of each draining ability... it's just a weird argument to make for a class since all of them have access to the gear, not just the Lich King. Also, that set is pretty much garbage.

Ah well...