Impassioned Orator

Whenever another creature you control enters, you gain 1 life.

Rith, the Awakener

Flying
Whenever Rith, the Awakener deals combat damage to a player, you may pay {2}{G}. If you do, choose a color, then create a 1/1 green Saproling creature token for each permanent of that color.

Juniper Order Ranger

Whenever another creature you control enters, put a +1/+1 counter on that creature and a +1/+1 counter on Juniper Order Ranger.

Concordant Crossroads

Trostani, Selesnya's Voice

Whenever another creature you control enters, you gain life equal to that creature's toughness.
{1}{G}{W}, {T}: Populate. (Create a token that's a copy of a creature token you control.)