Strategies/Experienced

Traps
Once you have unlocked Marielle, you can begin using a particular trap setup I call the toxic swamp. This particular setup is great if you want to see stuff die without having too many monsters around. You utilize the Poison Leak trap room to give everything thousands of stacks of poison! By having multiple of this room setup next to each other. maybe in a 3x3 grid at the entrance of the dungeon, the enemies will step on multiple of them and activate 1-2 thousand stacks of poison PER ENEMY. This means tens if not hundreds of thousands of stacks of poison once the rooms reach level 30 ish.

Dark Lord Focused (Stall)
Several Dark Lords are excellent at being the main source of damage, namely Elizabeth and Marielle whose 1 mana ability both scale incredibly well into the late game. In these cases your entire goal is to build up whatever scales their 1 mana damage (for Marielle post level 14) and 4 mana damage for Elizabeth post level 14. For Elizabeth, it is vampire and levels, for Marielle, it's slow stacks from Frost Storms.

While your Dark Lord is dealing damage, you will be using your monsters and facilities to completely bring enemies to a halt so that your dark lord can do her job. As such, room wide stun skills like Earthquake are amazing.