Dawn

Fuse Flash+Hemorrhage to kill everything on screen, even while the the boss is invulnerable. Fuse a second Flash with Sacrifice to get extra bleed stacks to trigger Hemorrhage faster plus extra damage from curse. Spider Queen (you start with the balls for this from your characters) fused with Succubus gives you insane constant healing as long as you have enemies on screen. If you got the perfect balls so far you'll still have 2 slots left so you can get a third Flash and fuse it with Bleed for extra stacks to trigger Hemorrhage even faster, with your last slot you can get Bleed for an insignificant amount of Bleed stacks, Vampire for a bit of extra healing or Freeze for a bit of extra damage, none of these will really make a difference. Comp explained: Flash hits all enemies on screen every time it bounces, Hemorrhage deals 30% of enemy's max health as damage every 3 bounces, this means you'll kill any enemy in 12 bounces no matter how much health they have, I was able to reach depth 2000m in Endless Mode with this then I quit cause it felt like there was nothing left to do. Succubus heals you every time you hit a charmed enemy, thanks to the Flash fusion, all enemies are charmed at all times so you heal every bounce. Ethereal Cloak is the only mandatory passive, aim for the back of the screen to get lots of bounces and trigger lots of Hemorrhages. If you have any ideas on how to improve this build please let me know!