Dirk of suffering appendage

A Dirk shaped out of glass flies toward a creature within range. Make a ranged spell attack against the target. On a hit, it takes 1d4 slashing damage, and its speed is reduced by 5 feet until the start of your next turn.

The spell creates more than one Dirk when you reach higher levels: two Dirks at 4th level, three Dirks at 8th level, four Dirks at 12th level, five Dirks at 16th level and six Dirks at 20th level.
You can direct the Dirks at the same target or at different ones. Make a separate attack roll for each Dirk.
If you hit a creature multiple time with this Spell, you can stack the slow effect up to three times. (speed reduce by 15 feet until the start of your next turn)

Creatures with no limbs/extremities, that are used for mobility are immune to the slow effect.