Emperor's Dais

Emperor's Dais's ability — "When you conquer here, you may pay 1 and return a unit you control here to its owner's hand. If you do, play a 2 Might Sand Soldier unit token here." — breaks into three distinct parts.

"When you conquer here" is the trigger condition. It fires when you establish control over Emperor's Dais at the end of a showdown.

"you may" appears as the first part of the effect, so you decide whether to place the triggered ability on the chain at all when the condition is met.^[383.3.a] If you decline, nothing happens.

"pay 1 and return a unit you control here to its owner's hand. If you do, …" is resolution-time effect text. "Pay 1" is not a cost within instructions — those are identified by the "[do X] to [do Y]" template — so the ability has no cost at finalization.^[742.1] However, "return a unit you control here" requires you to choose a target unit during finalization.^[402.1] This choice is mandatory — if a legal target exists, you must choose one and cannot decline this step.^[402.3.b]

When the ability resolves, both instructions execute in sequence. First, "pay 1." What happens depends on the state of your rune pool:

Second, "return a unit you control here to its owner's hand" — the targeted unit is returned regardless of whether the Energy was paid.^[055] If the unit has left the battlefield before the ability resolves, it is not returned.^[405.1]

The "If you do" conditional — play a 2 Might Sand Soldier unit token here — only applies if both the Energy was paid and the unit was successfully returned. If either fails, no Sand Soldier is played.