Shilgengar and March of the Machines on the battlefield.
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'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.