Repel the Darkness
Instant
Tap up to two target creatures.
Draw a card.
A boon to those who cannot see in the dark. A bane to those who live in it.
Scott Chou
Rulings
If you target one creature and that target is illegal as Repel the Darkness resolves, the spell doesn't resolve. You don't draw a card.
(wotc • 2018-12-07)
If you target two creatures and they're both illegal as Repel the Darkness resolves, the spell doesn't resolve; you don't draw a card. If just one target is illegal, the spell does resolve; the remaining legal target becomes tapped (if it's untapped at that time) and you draw a card.
(wotc • 2018-12-07)
You may target zero, one, or two creatures. The creatures don't need to be untapped.
(wotc • 2018-12-07)
If you target zero creatures, all that happens is you draw a card.
(wotc • 2018-12-07)
Rulings
If you target one creature and that target is illegal as Repel the Darkness resolves, the spell doesn't resolve. You don't draw a card.
(wotc • 2018-12-07)
If you target two creatures and they're both illegal as Repel the Darkness resolves, the spell doesn't resolve; you don't draw a card. If just one target is illegal, the spell does resolve; the remaining legal target becomes tapped (if it's untapped at that time) and you draw a card.
(wotc • 2018-12-07)
You may target zero, one, or two creatures. The creatures don't need to be untapped.
(wotc • 2018-12-07)
If you target zero creatures, all that happens is you draw a card.
(wotc • 2018-12-07)