I finally have some experience with Hexeris (at least enough to write SOMETHING about him). He's certainly different than the other Skorne warlocks I've used, and with his epic version coming out, there's never been a better time to be excited about him!
His stats aren't really amazing (or terrible) all around. Average SPD, decent MAT, DEF, and ARM. Having 17 damage boxes actually puts him slightly above average in Skorne, and he has a few ways to heal himself. His FURY stat of 7 is really nice as well. Overall, his stats are pretty average or slightly above average.
His only attack is Gulgata, a moderate P+S weapon with reach. It has Beat Back, which is a nice ability that lets Hexeris move his opponent around some, either to push him into a more favorable position, or even to push him out of combat, if you'd like. Also, it has Life Drinker- if he kills a living enemy model, he can heal d3 damage.
I don't find myself getting into combat much with Hexeris, but it's actually not that bad if you do. P+S 14 will definitely get the job done, and with Beat Back to help move people out of combat if you'd like, Life Drinker will help keep him alive, and with Vampiric Reaving (look under Special Rules) he can really get a lot of Fury during his turn to be very effective. Of course, you aren't going to have that happen too terribly often, but even though it rarely occurs it's a nice addition.
Hexeris' feat is Dark Dominion. When an enemy living or undead model is boxed while in his control area, you gain control of them, they become undead, they can move three inches, make an attack, and then are removed from play. With luck, you can chain this through your opponent's army, getting a lot of value for a single death (although in practice, you're lucky to get even the one extra dead model per model you kill). With luck, you can drop an opponent's warbeast with some of your attacks, and get a free warbeast attack (with no lost aspects) on another of an opponent's models.
As I 've said, with some luck, this becomes a TERRIFYING feat. I mean, it can end a game sometimes. Usually, you'll use it to kill models that are blocking charge lanes, or get a few extra points of damage on something that you're having a hard time killing.
Death March: This spell tends to get used every game. Extra MAT and Vengeance is really helpful in a generally melee oriented army. You'll need the extra MAT often enough to make it worth using for that alone, but having the extra attacks from Vengeance, plus the extra movement can make even mediocre offensive units into something a lot scarier. Throw it on something first turn, and move it to something else when the time comes.
Obliteration: AOE 4 POW 15 attack. Decent damage and the AOE is nice, but at a cost of 4, you're not likely to cast it often during your games. However, on the feat turn, sending one of these into a group of enemies can really get you started on the right foot. I find I rarely cast this.
Psychic Vampire: This spell is incredibly helpful against some armies, and not nearly as useful against others. However, even with the 'less useful' armies, it still might be nice to cast right away and upkeep it. Whenever an enemy model casts a spell or uses an animus while in Hexeris' control area, they take a point of damage and Hexeris heals a point. This spell will put a definite limit on the lifespan of several units, including Greylords, Battle Mages, Hex Hunters, and Druids. It'll also chip away at those spell casting solos pretty quickly. The healing is a nice bonus that could occasionally keep you in the game.
Against warcasters and warlocks, it's not quite so strong, but how often do you find your opponent at 1 health after your turn? Often enough that this can really be a powerful spell.
Soulfire: This is a pretty solid spell. It's POW 12, but removes the boxed model from play if it kills it (effectively making it useless for your feat). However, if you kill a living non-soulless model with the spell, you gain a fury (effectively making the spell only cost a single fury to cast!). POW 12 is high enough to be deadly to most infantry, and with the extra fury you can get a lot of mileage out of this spell.
Soul Slave: Two parts to this one- first, the warbeast you cast it on automatically passes threshold checks. That's actually not so bad on its own, although with Paingivers and FURY 7 you're not going to be struggling horribly with managing it. However, in addition to that, Hexeris can channel through the model this spell is on. That's REALLY nice.
Throw it on a Bronzeback, and none of your Titans needs to worry about Threshold checks. Throw it on a Gladiator, slam something, and start casting at the knocked down models.
There are plenty of ways that this spell can be handy so it's probably good enough to say that you'll be throwing this on something from the very beginning and upkeeping it the entire time.
Vampiric Reaving: Hexeris can reave fury from enemy warbeasts if he's closer than anyone else who could do the reaving. Not only do you get extra fury, which is always really helpful for spell casting, healing, or holding for transferring, but you also deprive it from your opponent, who is going to be more restricted about doing those things next turn. Of course, this ability means that you'll want to keep Hexeris up towards the front line a little, but with the abilities he has to help heal himself, having him just behind the front line isn't such a bad idea.
Cyclops Savage: Other than the benefits the Cyclops Savage gives to the other members of your army, there isn't really any major synergy between the two. Perhaps making Soulfire more likely to hit would be nice, but there are probably better targets for Prescience. Soul Slave isn't really that helpful on the Savage either.
Molik Karn: Since Karn is so good in every list, it makes sense that he would work so well with Hexeris. Soul Slave is really nice for when Karn gets too far ahead. You can very effectively extend your spell threat range. The amount of pain Karn can dish out can really feed Hexeris' feat turn. Hexeris' 14" control area gives Karn the ability to operate even further out.
Titan Cannoneer: I really like taking a Cannoneer with Hexeris for a few reasons. First, the gun is very handy on the feat turn. Shooting into low ARM infantry can really effectively clear them out. Second, when you're in position to shoot the gun, you'll be in position to channel some offensive spells through (via Soul Slave). The shooting + offensive spells can make for a moderately effective ranged threat. Also, since Hexeris is likely to be fairly close to the front, Diminish is a very handy animus to have available.
Titan Gladiator: Another very strong choice for Hexeris. Soul Slave allows you to put an arc node equivalent right in the midst of your opponent's army, where, after a Gladiator's slam, you should have some very vulnerable targets to drop an Obliteration or a Soulfire onto. Using the Gladiator as any sort of wrecking ball for some spell attacks is pretty effective.
Paingiver Beast Handlers: Not really any major synergy, although you can run really beast heavy if you wanted, because Soul Slave removes the threat of frenzying from a beast. Of course, you'll end up taking these guys in almost every list you can take anyway.
Praetorian Swordsmen: Death March on these guys is really nice. They become MAT 8 with is really nice, and with Vengeance, they become quite a bit more threatening, especially to a nearby beast or jack. Moving from two attacks to a potential three, in addition to the extra movement potentially provided by Vengeance (and Side-Step, of course), Hexeris can turn this unit into a huge pain in your opponent's army. Certainly not a bad choice.
Agonizer: There's no special synergy with the Agonizer, but the extra durability that he could bring may be handy. Two less damage from living models may be the difference between alive and dead with Hexeris, you never know.
Ancestral Guardian: Not any particular synergy, but reach and potential to have extra attacks can make the Ancestral Guardian an effective starter during a feat turn.
Hexeris' tier list is called the 'Kingdom of Shadow.' It's a very non-restrictive list of models you can include, although to hit tier 4 you're required to take 2 units of Praetorian Swordsmen (giving them Advanced Deployment), Aptimus Marketh (who I'll review soon, and is an amazing choice), and at least two Cataphract units. The benefits (Advance Deploy, Advance Move, and an extended deployment zone) are all geared to get you to grips with the enemy faster, and combined with Death March and some strong beasts, this could be a very effective combination of tools.
Oh, and he gets to have all his upkeeps up on the first turn. That's just fantastic of course. I've heard about using a Soul Slaved Razor Worm to put a shot into your opponent's deployment zone Turn 1, but I haven't tried it yet, so I don't know exactly how helpful that is.
Since this list is fairly open, I'll try to get it on the table one of these days in the not too distant future. Looks like it could be very effective.
Overall, Hexeris is a fairly strong caster. You don't see him taken in a lot of major tournaments, because he isn't as 'easy' as some of the other strong Skorne casters. You'll want to take a strong melee-oriented army, with at least one good melee unit (even Swordsmen work here), and a beast that'll need to be up close. All three of his upkeeps will probably be in play the entire game, leaving Hexeris enough focus for a solid Soulfire shot. I think Aptimus Marketh is absolutely required to run Hexeris- the extra spell a turn can save you some focus (even if you're just recasting an upkeep so that Hexeris doesn't have to pay for it), and the occasional ability to upkeep spells can help Hexeris' fury go a long way.
You'll probably end up playing fairly close to the action, so you'll need to make sure to have some protection as well as focus to leave on Hexeris in order to transfer damage. He can heal himself, a couple of ways, which will extend his lifespan. I've been able to fairly successfully run Hexeris as a backfield caster, but it can be a little tough if your Soul Slaved beast gets heavily engaged.