Koyo, Goblin Rocket Scientist

Improvise, delve
Koyo, Goblin Rocket Scientist enters the battlefield with a +1/+1 counter on it for each
card exiled to cast it and a +1/+1 counter on it
for each nontoken artifact on the battlefield.
{x}{r}, {t}, remove X +1/+1 counters from Koyo:
For each of X random targets, roll a d6. Koyo
deals damage to that target equal to the result.
If Koyo is a target, roll a d10 instead.