Otto's Resistible Dance

Song and Silence: A Guidebook to Bards and Rogues (SaS)Updated Supplementals (3.0)

Otto's Resistible Dance is a D&D 3.5 spell (Enchantment (Compulsion)) from SaS. On class lists for Bard (Level 5), Bard Variant (Level 5), Divine Bard (Level 5), and others. Range or area: Close (25 ft. + 5 ft./2 levels); Saving throw: Will negates; Duration: Concentration (see text); Casting time: 1 full round.

School
Enchantment (Compulsion)
Casting Time
1 full round
Components
V, S, F
Range
Close (25 ft. + 5 ft./2 levels)
Target
One living creature/caster level
Duration
Concentration (see text)
Saving Throw
Will negates
Spell Resistance
Yes

You can play a tune so foot-tappingly appealing that everyone who hears it wants to jump up and dance.
In fact, unless your target makes a successful Will save to resist, that’s exactly what happens.
A dancing creature suffers a -2 circumstance penalty to its Armor Class, Will saves, Concentration checks, and Spellcraft checks for as long as you keep playing.
Focus: The caster’s instrument.