Thats one of my two other main delimma's. One is do i kill them for failing to prepare, cripple them, or just alter their fate for the worse? The second is how would i go about statting it up for sure? I have some ideas i think are good ones and ill post them here in a little but i'm eating right now lol.
To some degree it depends on who the caster is and what he specializes in, but lets assume hes primarily a spirit/thaumaturge. with a lore of 4 Great, Disciplone of 4 Great and +2 in control bonuses.
If his desired affect is the victor sells like heart explosion spell he needs. 38 shifts to garentee it works [ im trusting deads math here] To invoke a death curse you essentially use up all of your remaining physical consequence slots. but you said hes not gonna go down without a fight. so im going to arbitrarily assume that the sorcerer has already used up his mild and moderate consequences. leaving him a potential +14 from his severe and extreme. add that to his base of 6 and you've got a 20 to work with. if hes got any fate pionts he can drop thouse in as well. but a think a blanket strength 18 attack against them all is likly to be enough to scare them
SummationImpromptu death curse "
Die With Me!" 20 shifts 18 attack, 2 to hit the zone.
18 strength attack against everyone there
Uses your extreme and severe consequence slot. add the rating of any other consequences left and/or fate points.
At this strength it probably wont flat out kill any of them but it will definitly leave them with some consequences to remember.