Supply Caravan
Creature — Camel
When this creature enters, if you control a tapped creature, create a 1/1 white Warrior creature token with [[ keyword: "vigilance" ]].
Nils Hamm
Rulings
If you don’t control a tapped creature as Supply Caravan enters the battlefield, its ability doesn’t trigger, even if you can tap a creature right away. If you control no tapped creatures as the ability resolves, nothing happens.
(wotc • 2017-04-18)
If an effect causes Supply Caravan to enter the battlefield tapped, it will satisfy its own triggered ability.
(wotc • 2017-04-18)
Rulings
If you don’t control a tapped creature as Supply Caravan enters the battlefield, its ability doesn’t trigger, even if you can tap a creature right away. If you control no tapped creatures as the ability resolves, nothing happens.
(wotc • 2017-04-18)
If an effect causes Supply Caravan to enter the battlefield tapped, it will satisfy its own triggered ability.
(wotc • 2017-04-18)