This is why i like 11 the most, hard, but fair with actual challenging bosses, since 13's only OP boss -tentacle boss- got nerfed to the ground.

There're so many different attacks in enemies on ch.11 compared to 13 (laser beams, pression with melee skeletons, bouncing scythes, spawner blob, teleporting knights, , homing orbs AND red projectiles VS... everybody literally shooting projectiles with the exception of the bees(that still shoot them anyways) and the occasional meteor wizard and fire crocodile)

Oh and to answer your question... you have to rely on luck by getting the best counter, Through the Walls, altough PC, frozen bracelet and some freezing abilities can help too.