If multiple sources deal damage to a creature with an enrage ability at the same time, most likely because multiple creatures blocked that creature, the enrage ability triggers only once.

If lethal damage is dealt to Indoraptor, its enrage ability triggers. Use Indoraptor's power from when it was last on the battlefield to determine how much damage it deals to the chosen player if they don't sacrifice a nontoken creature.

Indoraptor, the Perfect Hybrid's bloodthirst ability counts all damage dealt to your opponents this turn, not just damage dealt by sources you control.