Kilnspire District

When you planeswalk to Kilnspire District and at the beginning of your first main phase, put a charge counter on Kilnspire District, then add {R} for each charge counter on it.
Whenever chaos ensues, you may pay {X}. If you do, Kilnspire District deals X damage to any target.

Planechase Anthology Planes

When you planeswalk to Kilnspire District or at the beginning of your precombat main phase, put a charge counter on Kilnspire District, then add {R} to your mana pool for each charge counter on it.
Whenever you roll {Chaos}, you may pay {X}. If you do, Kilnspire District deals X damage to target creature or player.

Planechase 2012 Planes

When you planeswalk to Kilnspire District or at the beginning of your precombat main phase, put a charge counter on Kilnspire District, then add {R} to your mana pool for each charge counter on it.
Whenever you roll chaos, you may pay {X}. If you do, Kilnspire District deals X damage to target creature or player.

When you count the number of charge counters on Kilnspire District, count all charge counters on it, not just ones you put there.

You choose the target of the chaos ability as you put that ability on the stack. When the ability resolves, you choose a value for X and decide whether to pay {X}. If you do decide to pay {X}, it’s too late for any player to respond since the ability is already in the midst of resolving.