Squig, Maniacal Mouse

When Squig, Maniacal Mouse enters the battlefield, create Shmearbuckle, a legendary 1/1
black Rat creature token (abilities on token).
Backstabber — Whenever a creature you control
dies, put a +1/+1 on Squig, Maniacal Mouse. If
Squig, Maniacal Mouse has 10 or more +1/+1 counters, transform it.
This can't end well.