Fell Drain hits once, useful for low level one hitters but a waste of Metamagic room on DoTs. Also Bo3T causes it's boom when the Spell concludes, not before or during, through the half-Sonic property is pretty nice regardless.
Anyway, pretty much apply the normal. Snowcast/Dragonic Aura/Icemail for +6 to the Save DC in the later levels so it works more often than it fails. You can also run the standard on optimization Charisma like a Wand of Righteous Might (+4 sacred for cl/hrs), use Metamagic song to Persist Nixie's Grace (+8 enhance), Runestaff up some access to Devil's Ego (+4 profane), and see how the DM feels about Horseshoes of Flame (+4 unnamed). If you want to tack on damage, hook into Snowcast with Cold Spell Specialization & Cold Snap for +3/die, Dragonlance's Warmage for +3/die, apply Energy Substitution(fire) for Raging Flame+Caustic Mire+Searing+Ring of Mystic Fire for 4d6 & +3/die, apply Energy Substitution(electricity)+Stormcaster's Thunderbolt+Ring of Mystic Lightning for +4d6 & +X sonic & stun, or apply them all but you'll really wreck havoc with the balance of the game.
The main deal through, you'll want to use Protege. It grants you a pool of +1s equal to twice your CL which can be applied to your Perform Check in any amount from +0 to +(1/2 cl). This variable addon can be used to aim for specific outcomes on Fugue, specially when combined with something that sets the die roll. Such as Dervish 1 (take 10 on perform[dance] but fugal doesn't appear to care which perform is used), Surge of Fortune (take 20), or Exemplar (take 10). In the Mind's Eye Archived there is a lower level Power that lets you take a specified value too.