For the 'stack armor' method.
If mission does not assist when Zaalbar doing a turns, you can get to 8-9 armor shred stacks, and then go super hard on the Malak and kill.
With mission zeta, you won't get more than 2-3, or bit more if you like cheesy stuff.
Personally, I did it with mission zeta and with the stack armor method. with 5-6 armor shred stack (I think) by using cheese mechanics - before Zaalbar armor shred, use Mission special on Malak. She don't deal damage, She get feared, and she won't assist.
Mission zeta is still amazing tho. If you wanna wait to do it after malak event it's fine. If you wanna zeta her before it's also fine, just bit harder to do the event.