Tome of the Ancient Squizards

When Tome of the Ancient Squizards enters the battlefield, create a 1/1 blue Squirrel Wizard
token and a 1/1 green Squirrel token.
At the beginning of your upkeep, if you control a Squirrel Wizard creature, put an Acorn Counter
on Tome of the Ancient Squizards.
If there are 4 or more Acorn Counters on
Tome of the Ancient Squizards, Squirrels
you control have +2/+2.