So for anyone still deciding to give into nostalgia and play TL2 with synergies I kinda wanted to make a review on it. First of all half of the fun playing this comes from figuring things like mechanics and builds out on your own. Since all the forums are down and even the base mechanics of torchlight 2 aren't really explained well anywhere your most powerful tool becomes the wayback machine. Because of this I wanted to share some of the things I've learned about the mod that will maybe enhance your experience with it.

To be honest Vanilla TL2 is garbage by todays standards. With synergies mod though there are a lot of improvements to make the game still worthwhile. One of these improvements is that the mod adds and actual endgame with a really good progression system and a lot of different items and item sets to play around with. In short:
- get to level 100
- farm T0 gear in the Derinkuyu raid
- soulcraft T0 gear
- farm and soulcraft T1 gear in the Darknessfalls raid until you get bored

The mod says it's balanced around elite difficulty but I advise against playing everything on elite. If you are into very grindy gameplay and plan on playing one or more months then go with elite. Otherwise I'd suggest leveling on casual difficulty or even skipping leveling via console after you're finished with the story at around lvl 50. Embersteps is probably the best for leveling and also the most engaging. It pays off once you finally reach 100.
Try farming Derinkuyu on elite difficulty first. It's hard but doable. However if you wish to continue with Darknessfalls on Elite then you have to soulcraft your T0 gear which takes a long time. You probably need at least 8 angelic souls which equates to salvaging 400 legendary items and they usually only drop from bosses. If you want to skip this step then you will probably have to drop in difficulty for T1. Darknessfalls is still very hard even on casual difficulty. It's just a matter of how much time you are willing to spend for one boss initially. With T0 gear on elite the T1 bosses can easily take you 20 to 60 minutes to kill and then they might not even drop anything.
You can change the difficulty at any time either by creating a LAN game or by using the console.

Regarding the classes probably everyone can do Derinkuyu on elite but when it comes to Darknessfalls I found that only a few are viable. Keep in mind that the class evaluations are from my observations and there may be mechanics or playstyles that I simply do not know of. I have not actually played all of them, mostly just looked at the skills.
I found facetanking to be the best strat most of the times. Kiting and dodging just feels awful with the clunky character controls and you have to give up so much dps time it's rarely better than facetanking. One of the worst things about TL2 is that you can't have a dedicated move key so you always start to accidentally auto attack enemies when you want to run away instead.
When I speak of procs what I mean is that auto attacks and certain skills (usually the ones that do % weapon dps damage) can proc. As far as I know the best proc is glacial spike. There is a unique item Hammer of Retribution that has a chance of 25% to cast glaical spike which is probably one of the best weapons in the game and you can buy it from a vendor in Table Mountain.
And with sustain I mean the ability to recover life.


Embermage
Good damage, very good procs, best mobility but sadly no sustain at all. Really good in T0 with a shield but just dies in T1.

Beserker
Imo the best class, really good damage and procs with wolfpack and huge built in armor reduction which helps a lot in T1. On top of that 12% life regen as long as you crit. Just needs enough max health and mana / mana regen.

Engineer
Has a big damage absorb skill to make up for low sustain but lacks a bit in damage and procs. Probably still viable for T1 though.

Necromancer
Probably good damage and procs but almost no sustain. Minions can maybe make up for it but I've read that they die too fast in T1. Will probably have a hard time at the start of T1 but might be really good once geared. However no sustain is no sustain.

Paladin
Has strong buffs and passives but seems to lack a skill to do consistent damage and procs with. Still in development so things may change.

Ranger
Good sustain with tree of life. Good proc skill but you can't use Hammer of Retribution for it. Has really strong DoT passive. Extra max health. The melee spec revolves around auto attacking and can give you almost infinite sustain but lacks in damage and procs. The two minions are actually strong too.

Outlander
Has a bit of sustain with Stone Pact and maybe good damage and procs but probably just a worse embermage honestly.

Warlock
Decent sustain with mana field and damage absorb skill. Extra max health. Decent damage and procs with mana missiles. Strong passives especially the three extra procs. Overall good class but less dps than beserker. Only real downside for me is the bug that you frequently need to quit and resume the game to get rid of those fps freezes on every mana missile.

To conclude my top recommendations are Beserker and Warlock (I've killed all T1 bosses on Normal difficulty with them). Engi and Ranger are probably fine too. If you are feeling adventurous you can try and make paladin or necro work. I advise against Embermage and Outlander.


As for gearing, while leveling just pick up whatever uniques you find. Look for items with a lot of stats or damage on them and weapons with high dps. At lvl 100 if you are using a shield then I highly recommend going for the Adamant set. There is also a unique helmet with 20% damage reduction which will serve you well into T1. Which set you pick doesnt really matter that much. What matters is how many gem slots are free after capping damage reduction at 75% and getting the mana regen you need. You want to fit as many max health gems as possible while also getting a few 10% all damage gems or stat gems and some missile reflection too to prepare for T1. Reflecting missiles actually negates the damage.
I don't know how armor works but I know that mobs and bosses in Darknessfalls can have enough armor to negate all of your damage at which point you have three options: Somehow get more damage, try armor reduction on hit gems, try DoTs (they usually stack per hit) especially on weapon enchants. Or you can also just lower the difficulty at that point.
T1 gear wise the Draconic set seems way better than the others even when dual wielding. A few Angelic pieces for extra hp are also very good. Armor Pieces with + damage can significantly boost your weapons dps.

Casting parry means that you have significantly improved armor values but only for your next hit. It's a substitute for blocking.

In Derinkuyu you can drop vendor boon scrolls which are very valuable because from the summoned vendor you can sometimes buy the 7% damage reduction gem aswell as a special 5% and 3% one which you can combine to get the 7% one.

You get to Darknessfalls through Or'Ak pass and then Or'Ak basin. These maps don't drop good stuff and I've yet to find a way to reliably reset them so I never farmed these.
Also pay attention to your stats when you are in these regions. They apply debuffs and you will need more than 75% damage reduction to actually reach the cap there. I think it's 120% damage reduction in Darknessfalls to reach the cap. Things like dodge chance, block chance, damage, crit chance etc are reduced there too.

Soulcrafting T1 gear works like this: You need a special kind of soul stone that says it gives a bonus to a specific type and craft it with an angelic soul to get an imbued soul stone. Then go into embersteps and with the imbued soul stone in your inventory you can open the corresponding enchanting table. There you can place the T1 item and enchant it up to 4 times but it will cost a stone each time. You can also combine an uncut soulstone with the items you can buy from the npc in darknessfalls to make whatever type you need. Each boss and their adds can drop a different kind. Usually the enchant give 6% of the stat you pick but I havent confirmed them all. Health enchant gives you 750 max health and not 6% health.

In Darknessfalls there are also the challenge chest:
Trollking - kill the retainers and the second boss and open the callenge chest before you kill him
Abe - kill him fast enough
Dragon Rescue - keep dragon alive
Syrel'Khan - kill 15 spellbreakers before you kill him
The other challenges require you to not die but you can cheese them (quit / resume)


Some useful and almost mandatory links:

T0 drops, T0 soulcrafting and much more
https://www.kirmiziperfect.com/torchlight-ii-mods/synergies-guide/

T0 numbered bosses map corresponding to the link above
https://web.archive.org/web/20130708132133/http://forums.synergiesmod.com/index.php?topic=2448.0

T1 drop locations
https://docs.google.com/spreadsheets/d/1dW8PTu3ax8ebsJYnC5bmHmQrDdLtbiwF40k_y5N4D8A/edit#gid=432495281

Item database
https://tidbi.ru/Syn/eng/index.html


If any of these links are dead then try wayback machine. You can also try to search the old synergies forum on wayback machine but most of the threads arent archived.