This seems like a silly question at first because the answer should be "duh", but there's more to it and I'm a classic over-thinker (only in MCOC for some reason). There are 2 main reasons that I am hesitant to rank him up:
A. I already have 2 highly ranked mutants (R5 Namor and R2 Domino) in my top 5. Not a huge deal, but it leads to the more important, point
B. I don't
absolutely need him. Hear me out. Havok's 2 most attractive qualities are his high damage, and not taking damage from physical contact damage champs/nodes (korg, electro, psychic thorns, etc). However, Domino and Namor together satisfy these 2 things - Domino with the high damage and Namor with the hydrokinetic armor that reflects back damage (and high damage).
Havok is definitely OP, but with my already OP champs, is he worth the t5b?