Chimera Boss Fight Guide
Recommended Skulls: Ninja, Fighter, Grim Reaper, Mummy
You can get really close to the Chimera and attack its claws repeatedly, this is where a quick and heavy hitter like Ninja or Fighter comes in handy. You also might want to try with a ranged attacker, since you can get caught on the left side of the screen while the acid is falling from the roof. This will basically force you to stay away from Chimera and you could attack if you had a ranged Skull.
Grim Reaper is the perfect Skull to counter the small mobs that will fall from the roof from time to time. Simply use Harvest to take them all out swiftly.