Temur Charm
Instant
Choose one —
• Target creature you control gets +1/+1 until end of turn. It fights target creature you don't control.
• Counter target spell unless its controller pays 
.
• Creatures with power 3 or less can't block this turn.
Mathias Kollros
Commander 2020 (C20)
• #230Rulings
If the third mode was chosen, creatures with power 3 or less that enter the battlefield after Temur Charm resolves also can’t block. A creature whose power was 4 or greater when Temur Charm resolved but is 3 or less as the declare blockers step begins also can’t block.
(wotc • 2014-09-20)
If the first mode was chosen and either target is an illegal target when Temur Charm tries to resolve, neither creature will deal or be dealt damage.
(wotc • 2014-09-20)
If the first mode was chosen and just the creature you control is an illegal target when Temur Charm tries to resolve, it won’t get +1/+1 until end of turn. If the creature you control is a legal target but the creature you don’t control isn’t, the creature you control will get +1/+1 until end of turn.
(wotc • 2014-09-20)
You can’t cast Temur Charm choosing the first mode unless you target both a creature you control and a creature you don’t control.
(wotc • 2014-09-20)
Rulings
If the third mode was chosen, creatures with power 3 or less that enter the battlefield after Temur Charm resolves also can’t block. A creature whose power was 4 or greater when Temur Charm resolved but is 3 or less as the declare blockers step begins also can’t block.
(wotc • 2014-09-20)
If the first mode was chosen and either target is an illegal target when Temur Charm tries to resolve, neither creature will deal or be dealt damage.
(wotc • 2014-09-20)
If the first mode was chosen and just the creature you control is an illegal target when Temur Charm tries to resolve, it won’t get +1/+1 until end of turn. If the creature you control is a legal target but the creature you don’t control isn’t, the creature you control will get +1/+1 until end of turn.
(wotc • 2014-09-20)
You can’t cast Temur Charm choosing the first mode unless you target both a creature you control and a creature you don’t control.
(wotc • 2014-09-20)