One of the major complaints I've heard about the new Tyranid codex (we're back to this yes :P) is based around the Hive Tyrant and it's new counterpart, the Tyranid Prime. Many have advocated the use of the Tyranid Prime in nearly all situations compared to the Hive Tyrant with only the Swarmlord or Flyrants with Hive Commander being 'worth' it in terms of using the Hive Tyrant. This would make absolute sense if the Hive Tyrant was simply a combat beastie. In that regard the Tyranid Prime is almost as good for half the price. Whilst Hive Tyrants are obviously scary in close combat this is not why you take them to lead your swarm. Let's look at why.
The Tyranid Prime is a measly 80 points base and after some general purpose upgrades like Lash Whips, Bonesword, Regeneration and Toxin Sacs you're sitting at 115 points of pure combat awesome. In terms of point efficiency the Tyranid Prime is amazingly good for what it does. It improves any Warrior squads it joins and being an IC, can flit in and out of Tyranid units (something which the Tyranid codex lacks) including Carnifex broods. With regeneration you can easily chuck a wound on this guy early and hope for that lucky 6 but it makes other units more survivable and often easier to get cover (i.e. Carnifex Broods). However, this is all it really provides to the army. Whilst synapse is obviously important, the Tyranid Prime is first and foremost a combat character and will excel at this role.
The Hive Tyrant on the other hand is often a jaw dropping 200+ points and with Tyrant Guard is easily breaking 300. For that increase in points you don't gain that much in terms of combat ability. Whilst you're more survivable with T6/WS8/W4 + Tyrant Guard, your actual killing power hasn't been increased all that much. So what is the Hive Tyrant actually bringing to the table? First off the Tyrant is able to bring bigger guns to the table. 2xS6 devourers are very good at suppression fire and putting wounds on things whilst a heavy venom cannon puts out a high strength blast at range. These are obviously minor advantages for the Tyrant over the Prime but they are a key difference. Where the real difference lies is what the Tyrant does for the army. If we recall, the Prime is primarily a combat character and there is some utility provided for the Tyranid army through the Prime's IC status and synapse. The Hive Tyrant on the other hand is both a utility HQ and a combat beastie.
First off the Hive Tyrant has psychic powers. Whilst all of these aren't fantastic, paroxysm is amazing and one of the best powers in the game. Forcing any unit to WS and BS1 offers up a huge variety of choices and obviously makes your combat phase much more effective whilst also reducing damage in the coming shooting phase. Although this power is limited by range and the other powers the Tyrant has access to aren't fantastic, the combination of these powers allows for that little bit of extra flexibility in terms of gameplay. Furthermore, the Hive Tyrant has a lot more options available to it than the Prime in terms of 'biomorphs.' Things like toxic miasma, implant attack, acid blood, etc. are only allowed on the Hive Tyrant and aren't truly fantastic upgrades but worth mentioning for the custom happy go-getters out there. Although I wouldn't recommend armoured shell, being able to get a 2+ save is pretty big (though at 40 points...) whilst being able to get to S7 on the charge is important for anti-tank when dealing with all-round AV14 vehicles. The monstrous creature status is also huge for dealing with tanks in combat and we've already mentioned the increased variety of guns the Tyrant has access to as well as thorax swarm options. Add in the wings and the Hive Tyrant is more capable of fitting into different types of lists and meeting different types of threats. Again though this isn't really worth the cost of the Hive Tyrant compared to the Prime who is just a damn efficient combat character.
What the Hive Tyrant really excels at however is army buffing. Old Adversary and Hive Commander are two of the most important reasons for taking a Hive Tyrant and if you're not taking one of these with your Hive Tyrant, you should really re-consider why you are taking one. What these upgrades do is allow the Hive Tyrant to make a certain type of list better. Hive Commander obviously makes reserve based armies more reliable whilst Old Adversary makes a T6'R'Us list that much more potent as it simply advances across the field (re-rolling MCs, gants, Warriors, etc.? scary). These two abilities are the defining aspects of the Hive Tyrant and in combination with psychic powers, heavy guns and combat power makes Hive Tyrants a very good yet expensive HQ.
All in all the Hive Tyrant and Tyranid Prime play two different roles. Both provide synapse and the Tyranid Prime is a cheap and very effective combat character which can move between units (especially Carnifexes) and boost Warriors to be even more effective. On the other hand the Hive Tyrant is just as scary in combat but not very cheap. This expense makes you more survivable and more potent but at the same time offers the army a lot more options and army wide buffing abilities. If you're not looking for this and importantly aren't taking full advantage of abilities like Hive Commander or Old Adversary, don't take the Hive Tyrant as it becomes quickly inexpensive and you're not gaining an efficient return on your points. If you are looking for a scary combat creature which also buffs your army and getting benefit from Hive Commander or Old Adversary, the Hive Tyrant is an excellent buy.
