Kruin Striker

Whenever another creature you control enters, Kruin Striker gets +1/+0 and gains trample until end of turn. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Vigilante Justice

Whenever a Human you control enters, Vigilante Justice deals 1 damage to any target.

Plains

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Thatcher Revolt

Create three 1/1 red Human creature tokens with haste. Sacrifice those tokens at the beginning of the next end step.

Elite Vanguard

Sol Ring

Kessig Malcontents

When Kessig Malcontents enters, it deals damage to target player or planeswalker equal to the number of Humans you control.

Mountain

Commander's Authority

Enchant creature
Enchanted creature has "At the beginning of your upkeep, create a 1/1 white Human creature token."

Champion of the Parish

Whenever another Human enters under your control, put a +1/+1 counter on Champion of the Parish.

Riot Ringleader

Whenever Riot Ringleader attacks, Human creatures you control get +1/+0 until end of turn.