Omg you guys, it worked! I feel like a super modder now...
All I had to do was replace "magic_diversion" with "effect_stun." Worked great. No pause or anything, it just made the noise, showed the stun effect and the Skeleton lost his action points. Try it out if you want.
Manual Method
In addon_arena.lua, line 1010. Replace:
Code:
Attack.atom_spawn(act, tend, "magic_diversion", Attack.angleto(act))
with
Code:
Attack.atom_spawn(act, tend, "effect_stun", Attack.angleto(act))
Update: The attachment which replaces the "Fit of Energy/Rally" graphic with the "Stun" swirling stars effect has been consolidated into my other mods
here.