Other fixing options like Campus Guide, Grow from the Ashes, and Goldvein Pick are generally mediocre
First Strike 702.8
If you feel the deck needs more sacrifice outlets, Vraska, Golgari Queen is a fantastic planeswalker that would love to eat a Squirrel or three
However, you just can't count on always raiding
According to the lore text at the bottom of the card, the creatures are trapped on a rock (possibly an asteroid.) Someone left behind an encrypted log recording the existence of slivers, either an unlucky explorer or, perhaps, a scientist involved in experimenting with the creatures, which would be a nice callback to the Riptide Project
The ETB damage keeps early boards under control, and if you cast it normally, youre left with a double strike creature that closes games quickly