When do you declare targets/make choices - when playing a card or upon resolution?

Ruling: Targeting and costs occur when an effect goes on the chain. Choices that are part of the effect (not costs) occur upon resolution.

Sequence:

• When playing a card: Declare targets and pay costs
• Upon resolution: Make choices that are part of the effect text

Nuances:

• Target on resolution may occur when a prior effect in resolution is needed to be able to target
• Split damage effects target units on play, but the actual distribution between those units is decided on resolution
• Secondary targets (like Dragon's Rage's second unit) are chosen on resolution
• Effects like "discard 1" that are part of the effect text (not costs) have the choice made at resolution