Corazón ”Bring the Heat!” achievement tip.

“Grease the Wheels” quest. Populate your team with Neutral (Good/Evil axis) members. Level up only Corazón and (minimally) a tank. All boss fights include an Orc War Wagon. Get your 9+ puddles, wait for the wagon health to be sufficiently low for a kill, and pop his Fiery Bombardment ultimate attack while the Wagon is impotently bashing the tank.