General Antonyms:
* Prevent
* Stop
* Quell
* Discourage
* Pacify
* Soothe
* Appease
* Reconcile
More Specific Antonyms:
* Reconcile: If you instigate a conflict, you might reconcile the parties.
* Mediate: If you instigate a conflict, you might mediate a solution.
* Suppress: If you instigate a rebellion, you might suppress it.
* Calm: If you instigate a panic, you might calm the situation.
* Harmonize: If you instigate discord, you might harmonize the relationship.
The best antonym will depend on the specific situation and what you are trying to convey.