Oracle

Enchantment 

2: Put a plot counter on Deadly Designs. Any player may activate this ability.
When there are five or more plot counters on Deadly Designs, sacrifice it. If you do, destroy up to two target creatures.

Tournooi-info

Legal in: Vintage, Legacy, Commander

Officiele rulings

3/16/2018
You control the last ability of Deadly Designs, no matter who activated the ability to give it its fifth plot counter.

3/16/2018
You must sacrifice Deadly Designs as its last ability resolves. However, you can choose zero creatures as targets if you want.

3/16/2018
If the player who controlled Deadly Designs as its last ability triggered doesn’t control it as that ability resolves, Deadly Designs won’t be sacrificed. The same is true if each of the ability’s targets are all illegal by the time the ability resolves. However, if it’s still on the battlefield and has five or more plot counters on it, its last ability will immediately trigger again.

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