Lurking Roper + Splinter Twin + Prosperous Innkeeper

Lurking Roper

Splinter Twin

Prosperous Innkeeper

How it works

1. Activate Lurking Roper by tapping it, creating a token copy of itself.
2. When the Lurking Roper token enters the battlefield, Prosperous Innkeeper's second ability triggers, causing you to gain 1 life.
3. Each Lurking Roper you control triggers, untapping themselves.
4. Repeat.