Do state-based actions check between each individual spell resolving on the stack?

State-based actions (SBAs) are checked continuously whenever a player would receive priority. Crucially, after each individual spell or ability resolves, the game checks SBAs before returning priority to the active player. This is governed by CR 704.3, which states that SBAs are checked when a player would receive priority, and CR 117.5, which explains that after a spell or ability resolves, the active player receives priority — but SBAs are applied first.

This means that if multiple spells are on the stack, SBAs are checked after each one resolves, not just after the entire stack is empty. Each resolution is its own discrete event followed by an SBA check.

Common SBAs checked at these moments include: a creature with 0 or less toughness being put into the graveyard (CR 704.5f), a player with 0 or less life losing the game (CR 704.5a), and a planeswalker with 0 loyalty being put into the graveyard (CR 704.5i).

Concrete example: Your opponent controls a 2/2 creature. You cast Lightning Bolt targeting it, then cast Shock targeting it, with Shock on top of the stack. Shock resolves first, dealing 2 damage (creature is now at 0 toughness). SBAs are checked immediately — the creature is destroyed before Lightning Bolt even resolves. Lightning Bolt then resolves with no legal target if it wasn't already targeting something else, or simply deals damage to a creature that is already gone to the graveyard.

This sequential SBA checking is fundamental to how the game resolves stacks and ensures that game-ending or permanent-destroying conditions are applied at the earliest possible moment between each resolution step.