When Blue Ahri pushes to a battlefield and the enemy unit has Deflect, is Ahri required to give a unit -2, and if so, must they pay the Deflect cost or can they choose not to give -2 instead?

Ruling: Ahri's ability will trigger and you must choose a target, but you are not required to pay the Deflect cost. If you choose not to pay the Deflect cost, the triggered ability will not finalize and will not go on the chain.

Sequence:

• Ahri's triggered ability activates when she pushes to battlefield
• You choose a target for the -2 effect
• If the target has Deflect, you decide whether to pay the Deflect cost
• If you pay, the ability finalizes and goes on the chain
• If you don't pay, the ability does not finalize and never becomes a chain item

Nuances:

• This rule applies to all triggered abilities (including reflexive triggers from spells like Icathian Rain and Falling Star)
• For reflexive triggers that create multiple instances, you declare all targets at once and decide which Deflect costs to pay before any resolve
• Once you commit to paying Deflect costs for specific triggers, you cannot change your mind during resolution
• This is different from spells, where Deflect costs are mandatory if you target a unit with Deflect
• Triggered abilities that don't finalize due to unpaid Deflect costs effectively never happened