The repel_spell block (repel_spell), and the cauldron bubbles once they have turned on Sabrewulf. They fly straight at the player, four units a frame along each of X and Y, cycling through four frames. They slow to one unit a frame while the player is in an archway (bit 0 of the player's +7, set by chk_plyr_spec_near_arch), except in the wizard's room. Gravity still applies.

In the wizard's room they vanish once the player is no longer either form of the knight -- object 0's type outside 16 to 79, as it is once he has died. Because the bubbles' record says room $B4 (cauldron_bubbles), in practice this test is only made for sparkles built into room $88 itself, if any are.

Whether they do harm depends on +13: the bubbles' starting record makes them deadly, but a room's repel_spell record starts with +13 clear.