Mordenkainen's celerity

Mordenkainen's celerity was a spell that improved the efficacy and duration of other velocity-altering spells.

Effects
If Mordenkainen's celerity was cast by the same person moments before a spell such as feather fall, fly, haste, jump, levitate, or spider climb, the magical speed granted by that spell and its duration increased by a factor of 25%. In case of feather fall, the speed could also be reduced by the same amount if the caster so desired. Additionally, a casting of haste following the spell affected more creatures.

The spell also improved the caster's defense against speed-reducing spells such as hold person, slow, and web, as well as magically induced paralysis.

Components
The spell required verbal, somatic, and material components. The material required was a small container filled with either centipede or millipede legs.

History
By the mid‒14 century DR, the spell was well-known and relatively common across Faerûn.