Maestro

Maestro
UnitThespianCost: 3ATK: 3 HP: 5
Your virtuosos cost ⓪ to play and gain "⤵ → Deal 2 damage to a building. ◎"
His enthusiasm is infectious.
NeutralFinesse Tech II



Card-Specific Rulings
As usual, you can't exhaust a unit as a cost to use its ability unless you controlled that unit at the start of your turn or if it has haste. So you had to have controlled your Virtuosos at the start of your turn in order to exhaust them to do 2 damage. It doesn't matter that they got the ability in the middle of the turn and it also doesn't matter when Maestro came under your control or if Maestro has haste. — Sirlin