Can you respond to your own spell on the stack before it resolves?

After a spell is cast and placed on the stack, the game follows the priority rules (CR 117.3b). The Active Player (the player whose turn it is) receives priority first. This means you can immediately cast an instant, activate an activated ability, or use a special action in response to your own spell before it resolves.

The key rule is CR 116.3b: after a spell or ability resolves, or after a player passes priority, the next player in turn order receives priority. But crucially, CR 117.3b states that after a player casts a spell, that player receives priority again — giving you the first window to respond to your own spell.

Both players must pass priority in succession without adding anything new to the stack before the top object resolves (CR 117.4). So if you act in response, your opponent also gets a chance to respond to what you just did before anything resolves.

Concrete example: You cast Lightning Bolt targeting an opponent's creature. Before it resolves, you notice the creature has a triggered ability you want to prevent. You can immediately cast a second instant — say, Shock — targeting the same creature in response to your own Lightning Bolt. Now Shock resolves first, then Lightning Bolt resolves.

This is a fundamental part of stack-based gameplay and enables powerful sequencing strategies, such as setting up your own triggers or synergies between your own spells and abilities.