Does Sneak Attack's end step trigger use the stack and can you respond to it?

Sneak Attack reads: 'At the beginning of the end step, sacrifice the creature put onto the battlefield with Sneak Attack.' This is a triggered ability (it begins with 'At'), and per CR 603.1, triggered abilities trigger off events and are placed onto the stack when they trigger. Like all triggered abilities, it uses the stack (CR 112.3a).

When the end step begins, the trigger goes on the stack. Both players receive priority in turn order before the ability resolves (CR 116.3). This means each player can cast instants, activate abilities, or otherwise respond before the creature is sacrificed. The creature is still on the battlefield at this point and can attack, block, or be targeted normally during that window.

One important note: the sacrifice happens when the triggered ability resolves, not when it triggers. If you respond by giving the creature indestructible or removing it from the battlefield in some other way before resolution, the sacrifice may still be attempted, but since sacrifice doesn't use the stack (CR 701.17), it cannot itself be responded to once the trigger resolves.

Example: You use Sneak Attack to put Blightsteel Colossus onto the battlefield during your main phase. At the beginning of the end step, the sacrifice trigger goes on the stack. Before it resolves, your opponent casts Doom Blade targeting Blightsteel — but Blightsteel has protection from black, so that fails. You could also respond by activating an ability to flicker it, removing it from Sneak Attack's 'memory,' potentially keeping it permanently.

In summary, because it is a triggered ability (CR 603.1, CR 112.3b), it fully uses the stack and both players have the opportunity to respond before the creature is sacrificed.