Just having this in play shaves off 1 mana for each creature you cast
Sacrificing Mutagen tokens also trigger that effect as well, as does returning cards to your hand with something like Sneak
Theres even another Otter later in the article thats perfect for the 99 of the deck
It's another non-in-universe take on an in-universe mechanic, considering its similarity to spree, the mechanic on cards like Three Steps AheadThree Steps Ahead from Outlaws of Thunder Junction
Witherbloom Pestilence Specifications Reasons to buy + Commander provides card draw, lifegain, and +1/+1 counters + Meticulous, grindy playstyle + Blows Witherbloom Witchcraft out of the water Reasons to avoid - Sacrificing smartly is a delicate art Witherbloom Pestilence is a Golgari (black-green) deck that focuses on an aristocratic strategy, sacrificing your critters for greater gain
The 'Standard' format was created to reduce the game's overall power (as well as entry cost) by limiting the legal cards to those from the last 4-8 sets