Kraken's Eye

• WWizards of the Coast2009-10-01
  Official Ruling
  If a player casts a blue spell, Kraken’s Eye’s ability triggers and is put on the stack on top of that spell. Kraken’s Eye’s ability will resolve (causing you to gain 1 life) before the spell does.
• WWizards of the Coast2009-10-01
  Official Ruling
  The ability triggers whenever any player, not just you, casts a blue spell.

Rulings via Scryfall