Activate Merrow Bonegnawer by tapping it, adding {B}.
Activate Viscera Seer by sacrificing Gravecrawler, causing you to scry 1.
Cast Gravecrawler by paying {B}.
Merrow Bonegnawer triggers, untapping itself.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Infinite scry 1

Infinite storm count

Gravecrawler

Merrow Bonegnawer

Paradise Mantle

Viscera Seer

Activate Merrow Bonegnawer by tapping it, adding {B}.
Activate Carrion Feeder by sacrificing Gravecrawler, putting a +1/+1 counter on Carrion Feeder.
Cast Gravecrawler by paying {B}.
Merrow Bonegnawer triggers, untapping itself.
Repeat.

Infinite +1/+1 counters on a creature

Carrion Feeder

Activate Merrow Bonegnawer by tapping it, adding {B}.
Activate Altar of Dementia by sacrificing Gravecrawler, causing target player to mill cards equal to Gravecrawler's power.
Cast Gravecrawler by paying {B}.
Merrow Bonegnawer triggers, untapping itself.
Repeat.

Infinite mill

Infinite self-mill

Altar of Dementia

Activate Merrow Bonegnawer by tapping it, adding {B}.
Activate Goblin Bombardment by sacrificing Gravecrawler, dealing 1 damage to any target.
Cast Gravecrawler by paying {B}.
Merrow Bonegnawer triggers, untapping itself.
Repeat.

Infinite damage

Goblin Bombardment

Combos with "Merrow Bonegnawer"