Spells: Selo's Consonant Chain and scarab mobs

[Jimjam]

The mob is sluggish and the snare is strong...

Perhaps the mob is becoming so snared it's speed clocks round below zero and the game interprets that to mean lightspeedahead?

I remember a bug in Baldurs Gate had a similar effect; if you cast a resist buff on highly resistant mobs the resist counter would loop back round to zero (making the mob highly nukable!).