Maybe a Wild Arcana'd Antimagic Ray instead,
@TotallyNotEvil?
Oh, that's nice. But where did you get Dim Anchor? Neither Malarys or Vee have it. Bloodwish?
Maybe:
[X] Plan Easy Does It
-[X] Viserys
--[X] Uses bracers for a Silent Stilled Bloodwish: Major Creation for a bit of phosphorus.
--[X] Uses Bracers again for a Silent Stilled Bloodwish: Symbol of Sleep. Set it so the Erynies aren't affected, and some trigger he can use as a free action, such as scuffing the symbol with his foot.
--[X] Discreetly uses his item to heal the charisma damage.
--[X] Assay SR on the Abishai, Triggers the Symbol and Wild Arcana a Potent (+2 CL/DC) Antimagic Ray on the Abishai and casts Arcane Spellsurge.
--[X] Stays at the ready with Mythic Initiative + Belt of Battle and Celerity if something unexpected happens, especially if he makes his save.
-[X] Vee & Malarys
--[X] When Viserys signals he is ready, they both Greater Dispel the Abishai as an opener (before Viserys uses AMR). Be ready to Alter Fortune if need be, such as in case of the AMR failing. Malarys can use a Quickened Boneshatter, too.
-[X] Ser Richard and the Furies
--[X] Charge and subdue it
-[X] Pick a monotonous bit of the sermon to act, at least a point where everyone is seated.