Copied from Endless Dungeon, Strategy
Stat growth in ED is insane. By the 20th floor, an enemy will have 41x their base hitpoints, 73.8x their base attack and defense, and 23x their base accuracy, evasion, and magic attack. For some perspective, the boss with the least accuracy and evasion is ?????, and he comes with 25,000 of both; that's 575,000. You would need almost 530,000 evasion to dodge any of his attacks, and 115,000 accuracy to hit him at all. For high evasion and accuracy, you would need almost 3 million and over 630,000, respectively. The boss with the weakest attack is the first form of Chimera, with 2,000,000; at floor 20, he would be sporting over 140 million damage. There is no point trying to beat these monsters in straight-up stat fights.
Points spent in Dexterity Enhancement, Invisible Armor, Overpowered Tanker, and Protection, are points wasted. (Unless you're trying to reduce drown damage, but if you are aggressively trying to go deeper, you should find that enemies kill you long before you can drown.)
Defensive skills that don't depend on overwhelming your enemy's stats are a must-have: Absorb, Explosive Attacks (for the stun), Magic Reflect, Revive, and Artful Dodger. You will need Accuracy Boost for the hit chance as well.
Recommended builds (10 means cap it, 5 means put as many points as you need, 1 means put points if you can spare them; anything else means use that exact number):
for ranged weapons
or for melee weapons
Recommended Ring: Depends on how far you're able to go. Enemy attack becomes very extreme in the deeper floors, arguing for a Combo Ring, but on the lower floors a Cruelty Ring is much better, if you are using a melee weapon Chronos ring is the best ring in all cases.
Recommended IA: Censor Sheep
Turn-Based Mode is recommended.
Censor Sheep Strategy
The Censor Sheep Strategy is currently widely regarded as the best strategy for deep runs in the Endless Dungeon. It centers around the Censor Sheep Invisible Ally, because of its insanely powerful abilities. CS gives a staggering 60% dodge and hit chance up front, and chipping and Ultraing the creature turn that into 150%. Combine with 50% from Accuracy Boost and Artful Dodger, and you're at 200%--only 90% from the theoretically perfect 290% that will allow you to cap those abilities all the way to the 200th (final) floor.
On top of those stats, CS also gives a slow-charging invincibility buff. A player can use another buff--mastery or power--until they receive a fatal blow from a monster, and then, while Revive is recharging, quickly turn off the buff to trigger CS's invincibility buff.
At the start of a long boss fight, using Quick Attack to build Crescendo instead of leading with Power Attack can slightly increase your damage; it only takes one second with QA, as opposed to about three seconds with PA or SKB. Remember to turn off Mana Power to save MP. Only do this in Turn-Based Mode.
PD: Most of these guides are fairly outdated, anyone is welcome to update them and please, sign with the version