Kilnspire District is a common Plane — Ravnica card from Planechase 2012 Planes (OPC2), collector number 23. Current market price: $2.50, TCGplayer market prices via Scryfall.
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.