Devoted Druid + Luxior, Giada's Gift

Prerequisites

Luxior attached to Devoted Druid. Devoted Druid does not have summoning sickness.

Steps

1. Activate Devoted Druid's first ability by tapping it, adding {G}.
2. Activate Devoted Druid's second ability by putting a -1/-1 counter on it, untapping it.
3. Because Luxior gives Devoted Druid +1/+1 for each counter on it, Devoted Druid's toughness remains unchanged.
4. Repeat.