This is because whenever a non-token shrine enters the battlefield under its owner's control, they create a 1/1 shrine creature token
Slime Against Humanity creates a 0/0 Ooze creature token with trample when you cast it, putting 2+X +1/+1 counters on it, with X being the number of cards in your graveyard or exile with the Ooze creature type or with the same name as Slime Against Humanity
I like this in the various Rakdos Aggro and Midrange decks that either dont care about their life total (Deaths Shadow) or plan on gaining back a bunch of life (Sheoldred, the Apocalypse)
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Its the perfect card to end this article on one that is going to do a lot of work for you in decks that care about keywords, like Odric and Kathril, in decks that care about delirium and Tarmogoyfs (think Disa!), and will also be a great option for late game or midrange decks that just want a nice incidental blocker
Can You Proliferate the Commander Tax