Ok so I'm approaching this differently now that I have a wider variety of figures.
But this list is still only based on what figures I actually have. My brother orders to use tooled up jolly ranchers like vextha with galeshi sunsword with harasser magespawn and a summoning fig.

398 pts faction pure+ 1 mage spawn

Rivvenguard Jaysa 65pts
Inferno 35pts
Cloak of the Dervish 37pts
Magestone Bracers 10pts

Geddion Longblade 55pts
Spirit Armor 40pts

Terk a 36pts
Relic breaker

Master archer** 38
Apprentice Conjurer ** 37
High elven archer *** 35

So the plan is to use Geddion, Jaysa, Terk to go after Vextha by way of:
1 if Geddion dies vextha dies
2 jaysa goes toe to toe with vextha and hopes for the best but with her improved stats and abilities she stands a better chance.
3 terk weakens vextha by removing his relic when his cc attack is unsuccessful.
The free army formations is fast an has improved range and damage and picks off other figs to let my main three go to work. The trio can still smack around weaker figs when vextha is dead.

** Rivvenguard archer is a great one to throw in if you can track some down. Zeph Wyndfenner is another great backup piece, leadership shouldn't be underrated. Or a nexus war bard for that matter.

So I changed my list above with my updated list. Based off of the figs I have

I know you're working off stuff you have, but just a suggestion based on stuff that's not too hard to get (and stay faction pure).
The biggest weakness I see is soaring ranged attacks. If you smack Vextha down to his bound clicks without killing him, he'll just pop up and regen/ bound-life drain your non-Jaysa figs. What items he puts on Vextha can change things a bit, but I think if you replace the formation of three with a Regal Skymage (any of the three will do, but if he has relics that stop ranged attacks or wand type don't use the three star) and Zeph Wyndfenner (one of my very favorite elves) or a nexus war bard/vindicator. Leadership is amazing, especially for your primary three hitters. Either of those three figs would be also be a good back up figure for spirit armor if you should need it.
There's also my favorite spirit armor wielder, Mistral. He soars, he's a bit slow (8) but he has 10 attack three damage and invuln. plus toughness. And he has but one click of life. So as long as you don't push him Vextha will never target him and he can harass him pretty well if Vextha retreats to the sky. Unless Vextha also has Inferno, then that wont work so well.

Pretty sure all of the above are currently on ebay. You're milage may very. Sorry for the mini novel but you've touched two of my favorite things in MK, elves and Vextha.

I once used Mistral/SA to tie up a flameshield wielding Kossak for an entire 500pt game. The rest of my force mopped up the rest of their figs (it was an all soaring charge/bound elf pure army) then took the tokens.

I have the vindicator ad was really considering him for leadership anyway. Ill look into the other two figures. Thanks.

This auction is easy to miss since it's spelled wrong, but a good deal.

http://www.ebay.com/itm/Lot-3-Collec...item231fb56334