the skycutter sea helm is a waste of points to be honest. unless you are playing joined profiles a t3 elf is always going to get ripped off any mount or out of any combat I will happily concede that the only effective way for us to take a bsb is either in a sky cutter or in a mage block. (out of combat). But if he's on the skycutter and doesnt want to be in combat (t3) then why do you have a skycutter that doesnt want to be in combat. (bow on skycutter is poo and you cant take it with sea helm anyway).
Your spread way to thin across your specials. Big Time. Pick an amazing unit, or one or two really good units that you have specific goals for. You could drop something out of your hero list....... then two units of any special unit that are going to do something. I'm HE so its a unit of 28 WL and 28 SM's with standard and cheap banner.
Love the frost heart, great utility, great monster.
This.
Unless you're going for a Lothern themed list (and even then you could just use the sea helm model as a regular noble), I wouldn't take a sea helm at all. Especially not on a chariot with a bsb - a noble is much cheaper and if you want a fast moving bsb then an eagle or regular horse will do the job just as well.
Could you tell us how many points you're looking to do this at? And if there's any specific theme you're looking to follow?
Looking at it for the moment it seems you're looking for all cavalry - that being the case I'd make a few recommendations:
1) Dark Riders - with shields and crossbows and a musician all for 110pts these make great chaff and harrassment units, use them to take potshots, hunt warmachines, and draw the enemy out of formation. I'd probably take your minimum core on these.
2) Warlocks from the dark elf list - I personally don't use them but the magic they bring can bring some nice buffs to your shooting via soulblight (which lowers S and T), as well as direct damage from doombolt too.
3) Cold One Knights and Dragon Princes - Personal preference with these I think... they both have 3 attacks each (I'm including the mount in that too), but the princes are slightly weaker at basic S3 rather than 4, but also a point cheaper... but they're also not stupid... Up to you with these, but whatever you do, I'd take a lot of them to really make an impact when they charge. I'd consider at least 2 medium-large units of these whichever you pick.
4) Wild Riders I've been experimenting with recently, and they're the quintessential glass cannon - whatever they charge absolutely needs to die/run on the turn they've charged, or else they'll get cut down next turn. Use them as flankers, and only commit them when you're sure to win.
5) I'd also suggest warhawk riders too actually as they're awesome at popping war machines since they're more resilient than a regular eagle.
6) Phoenix is awesome. I'd consider a second one. Always charge it in conjunction with your other stuff though to make your combats easier - looking at your list I'd guess it's around 2k upwards, so you're gonna be facing large infantry blocks, you're gonna have an uphill battle beating that with cavalry.
7) Finally....I think it might also be possible to bring a dragon in a list like this. They're not the most competitive choices sure due to being cannon magnets but if you can saturate said warmachines with important targets first (i.e. fast cavalry) then the dragon can possibly evade some fire...don't put a wizard on it though... or if you absolutely must do it with a couple of dragon-mages and bring more than 1.
Anyway - that's my 2 pence!