×I am aware of two different methods for killing all the goblins. The easiest method involves starting with your sword East or West at first. At some point you might need to move north when a mimic is blocked by goblins so you have space to perform a move like E then SW to kill goblins on one side and keep them caught against the mimic on the other.

×All 5 mimics are needed, fiddling about with movement order tricks is unnecessary. The intended solution is very straightforward.