When Mulrektir enters the battlefield, tap
any number of target permanents that have insanity counters.
Mulrektir is hexproof and indestructible as long as you have insanity counters.
Trample
2(B) gain control of target permanent with insanity counters. Untap it.
5(b)(b) destroy any number of target permanents with insanity counters. Permanents destroyed this way are exiled.
Embrace the feeling, for it is all that will ever remain.