Instant Death

Instant Death is a debuff in Xenoblade Chronicles. It deals damage equal to the victim's current HP.

Obviously, Instant Death is a very dangerous debuff, as it simply kills the receiver without defensive abilities coming into play. However, because it is a debuff, being resistant or immune to debuffs means it can be avoided entirely. It also still triggers gems and the Damage Immunity buff, which both allow survival. All bosses and unique monsters are immune to Instant Death.

Instant Death is commonly used on enemy arts where the foe suicides, either to explode and deal extreme damage, or to "hatch" into a different enemy. (Enemies that are immune to Instant Death can therefore explode without detriment to themselves.) Enemies that suicide do not drop chests or provide rewards (e.g. EXP). Using Reflection to turn an Instant Death attack back on the foe counts as a suicide.