Detonator

The Detonator is an Emblem Heartless that is found in Kingdom Hearts 358/2 Days.

Strategy
The Detonator has the highest defense among the other "Bomb" Heartless and counts down more frequently. The explosion it makes is also the biggest, so it is best to attack it from afar. Also note that freezing a Detonator while it is counting down will freeze the countdown.