Marvin, Murderous Mimic + Phyrexian Devourer + Triskelion

Marvin, Murderous Mimic

Phyrexian Devourer

Triskelion

How it works

1. Activate Marvin using Phyrexian Devourer's ability by exiling the top card of your library, putting a number of +1/+1 counters on Marvin equal to the exiled card's mana value.
2. Repeat step 1 as desired or until you have an empty library.
3. Activate Marvin using Triskelion's ability by removing a +1/+1 counter from Marvin, dealing 1 damage to any target.
4. Repeat step 3 as desired.