Mazirek, Kraul Death Priest

Legendary Creature — Insect Shaman

Flying
Whenever a player sacrifices another permanent, put a +1/+1 counter on each creature you control.

2/2

2020-08-07:
A legendary permanent that is put into a graveyard because of the “legend rule” isn't sacrificed.
2020-08-07:
Mazirek's last ability is a triggered ability, not an activated ability. It doesn't allow you to sacrifice a permanent whenever you want; rather, you need some other way of sacrificing permanents.
2020-08-07:
If you sacrifice a permanent as part of casting a spell or activating an ability, Mazirek's last ability will resolve before that spell or ability.
2020-08-07:
If you sacrifice Mazirek and other permanents at the same time, Mazirek's last ability triggers for the other permanents.