Dr. Cornelius Livingston

At the beginning of your upkeep put X 1/1 squirrel tokens with forestwalk onto the battlefield where X is the number of Squirrels you control
squirrels you control get +2/+2 and have trample
Horses you control get hexproof, menace, and forestwalk
At the beginning of your end step put X 3/3 horse tokens with Trample onto the battlefield where X is the number of horses you control