You have a way to cause a creature to enter the battlefield under your control.
Scurry Oak has at least one +1/+1 counter on it.
({1} magic symbol) available.
Steps
Cause a creature to enter the battlefield under your control.
When the creature enters the battlefield, Tainted Observer and Mana Echoes triggers.
Resolve the Mana Echoes trigger, adding ({C} magic symbol) for each creature that shares a creature type with the creature that entered the battlefield.
Resolve the Tainted Observer trigger, causing you to pay ({2} magic symbol) to put a +1/+1 counter on Scurry Oak.
Scurry Oak triggers, creating a 1/1 Squirrel creature token.