Portal Knights

Once you enter the world you run up the stairs and there is a flaming egg on the platform. Whack the egg, no matter how (arrow, spell, hit it, etc.), and the egg gets launched from the platform. This makes the boss to show itself.

The boss has 2 phases which toggle until the boss is dead.

First phase, the boss is immune to attacks and shoots eggs. Don't get hit by them and do some evasive maneuvers. The eggs stay on the platform, ensure to whack the eggs. If they hatch additional enemies will appear, they will hatch once you go from phase 2 to 1.

Second phase, the boss will lay itself on the platform and you able to attack it. Give everything you have and nuke it!

Rinse and repeat!