Triggered effects with cost

[spiritomb_]

Why do some triggered effects that have costs with them get paid when the effect is placed on the chain, and some of them are paid after? For example n948 Temari & Gaara of the Desert says "When this Ninja is put in play, your opponent discard their hand. In that case..." The in that case denotes a cost, but it was ruled that they do not discard their hand as a cost for the effect.

[Laughing_Man]

Originally Posted by spiritomb_

Why do some triggered effects that have costs with them get paid when the effect is placed on the chain, and some of them are paid after? For example n948 Temari & Gaara of the Desert says "When this Ninja is put in play, your opponent discard their hand. In that case..." The in that case denotes a cost, but it was ruled that they do not discard their hand as a cost for the effect.

has a triggered effect. It does not have a cost.
Costs are always optional. This means that you will always choose whether or not you want to pay the cost for something. There are no effects in this game that forces a player to pay a cost.

"In that case" does not always denote a cost. If an effect has a cost, there will always be followed by "in that case." The opposite is not true. Just because an effect has "in that case" does not mean that whatever sentence preceded it is a cost.