You control a permanent that is boosting the toughness of all your creatures by at least 1, or that is giving a creature a +1/+1 counter as it enters the battlefield.
You control at least one additional creature.
Steps
Activate
Shilgengar by sacrificing
Tom, Bert, and William.
When
Tom, Bert, and William die, they trigger, returning them from your graveyard to the battlefield as a noncreature artifact.
Because
Tom, Bert, and William enter as a noncreature artifact,
March of the Machines will then cause
Tom, Bert, and William to be a 5/5 artifact creature.
Resolve the
Shilgengar ability.
Repeat.
Activate
Shilgengar's first ability by sacrificing another creature, creating a Blood token.
The Blood token enters the battlefield as a 0/0 creature due to
March of the Machines, and will have its toughness boosted by the permanent specified in the pre-requisites to prevent it from dying.
Repeat.
Results
Infinite Blood tokens.
Infinite ETB.
Infinite LTB.
Infinite death triggers.
Infinite sacrifice triggers.
Metadata
In 0 decks according to EDHREC.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).