Auriok Sunchaser

For the purposes of blocking (either because Auriok Sunchaser is attacking or because a creature with flying is attacking Auriok Sunchaser’s controller), whether Auriok Sunchaser has flying is checked only as the declare blockers step begins.

If Auriok Sunchaser blocks a creature with flying, causing it to lose flying (by destroying an artifact its controller controls, for example) won’t change that.