Thorn of the Black Rose

Set
Conspiracy: Take the Crown
Rarity
Common
Text
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.) When Thorn of the Black Rose enters the battlefield, you become the monarch.
Legality
Legal in: Commander, Duel, Legacy, Pauper, Vintage
Rulings
2016-08-23: The game starts with no monarch. Once an effect makes one player the monarch, the game will have exactly one monarch from that point forward.

2016-08-23: Abilities that trigger whenever you “become the monarch” trigger only if you aren’t already the monarch. For example, if you are already the monarch as Custodi Lich enters the battlefield, its last ability won’t trigger.

2016-08-23: If the triggered ability that causes the monarch to draw a card goes on the stack, and a different player becomes the monarch before that ability resolves, the first player will still draw the card.