Temporarily eases relations with the target nation.
It works much like the Bard Archetype ability, Soothing Song. The Diplo Dervish will temporarily raise your relationship with another nation to a Blue Face. It very useful when playing economically, so you can keep your trade routes up. It also helps when trying to finish with a Diplomatic takeover, simply making Alliances when playing religiously. Even military nations may find a use for it; they could keep an enemy nation at peace for a time while they finish off another nation. However, most players who use military action in the Civilization Stage typically do not socialize in the Creature Stage.