You control a creature that has power equal to 6, that doesn't have summoning sickness, and that cannot be blocked by an opponent.
Steps
At the beginning of your combat phase,
Ayara triggers, returning
The Aetherspark from your graveyard to the battlefield.
Activate
Brass Squire by tapping it, attaching
The Aetherspark to a creature you control that has power equal to 6.
Deal combat damage to an opponent using the creature that has
The Aetherspark attached, triggering
The Aetherspark, putting six loyalty counters on it.
Activate
The Aetherspark's third loyalty ability by removing ten loyalty counters from it, adding ten ({R} magic symbol) .
The Aetherspark is put into your graveyard as a state-based action due to having 0 loyalty.
Activate
Aggravated Assault by paying ({3} magic symbol) ({R} magic symbol) ({R} magic symbol) , causing you to untap all creatures you control and to get an additional combat and main phase after this one.