Kilnspire District — ruling 1

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.

Kilnspire District — ruling 2

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

Kilnspire District : règles, fonctionnement et interactions (MTG)

Kilnspire District is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

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

How it works : Kilnspire District

Original English text — Wizards of the Coast / Scryfall

#1June 1, 2012· Wizards of the Coast
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 . If you do decide to pay , it’s too late for any player to respond since the ability is already in the midst of resolving.
No other card is named in this ruling.
#2June 1, 2012· Wizards of the Coast
When you count the number of charge counters on Kilnspire District, count all charge counters on it, not just ones you put there.
No other card is named in this ruling.