The following MTG sets have one squirrel each: Kaldheim , Strixhaven , Outlaws of Thunder Junction , and Ikoria: Lair of Behemoths
Decks that play their opponents' cards are great for adjusting to the power level of a table because you really are at the mercy of what your opponents bring
Thats certainly true in Foundations, but it also gets a number of other potent tools as well
Because similar to a commander in EDH, you can always count on having it available without having to draw it, which is very powerful
While it can be a useful card in certain situations, there are better options available such as Palace Jailer which not only makes you the monarch but also exiles a creature
It isn't attacking as a 3/4 until turn 6 which is both a bit late and a bit small