When can I play Intervention Pact?

[RainbowPenguin]

Intervention Pact, according to Gatherer:
"The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.

At the beginning of your next upkeep, pay 1WW. If you don't, you lose the game."

I'm considering this for Hive Mind, and I want to know if there are any restrictions on when I can play this Pact? I.e. as "a source of your choice", can I name, say, an Island I control?

[Malchar]

You can play it any time you have priority just like any other instant. On resolution, you choose any game object as the source, which could be an Island.

[RainbowPenguin]

Thanks for the answer!