Give material to deliver mate or win more material
Give up material for a forced sequence that mates, wins more back, or leads to a won endgame. Calculate it through: pretty sacrifices are usually unsound.
Queen lands on f7 with check.
3 more clean runs (at any point) to reach Recall.
Black king on g8 has rook on a8. The f-file is open for white.
3 more clean runs (at any point) to reach Recall.