Maleceptor
History
In late October 2014 GeeDubs made a token attempt to help the Tyranids feel less useless and released two more monstrous creatures, one of which was the Maleceptor. Described as just being an extra large Zoanthrope with extra armor and some legs because lifting something that much bigger requires more effort because of the square cube law. Though the real reason is because it shares the same model pack with the much more useful Toxicrene, with the Maleceptor growing six exposed brains out of its back instead of the Toxicrene's pus sacks.
Tabetop
Seventh Edition
Anyway, while the Toxicrene was at least decent, the Maleceptor became incredibly unpopular within minutes, clocking in at 205 points with only 4+/5++ and Mastery Level 2. Its big gimmick is a unique power called Psychic Overload, and can cast it on three different targets a turn. It brings back memories of the old Doom of Malan'tai what with target takes a Ld test on 3d6 or else take d3 wounds with AP2 Ignores Cover. Only problem: it's Warp Charge 2. Go ahead and do some test rolls to see how many warp charge dice you need to make three WC2 powers (answer: 4 charges per shot, if you want better odds than a coin flip). Also it's a Focused Witchfire power, which means A) you need THREE warp charges to actually kill the important target instead of some random schmuck, so you're dropping even more warp charge dice, and
B) most opponents will force you to roll to-hit. Did I mention the Maleceptor is only BS3? (This has been changed in the Rulebook Errata v1.2 "However, some witchfire powers do not have a weapon profile (such as the Telepathy power, Psychic Shriek); where this is the case, no To Hit roll is required – the attack hits automatically".)) And of course, Deny the Witch can make it useless even when it does hit so all those warp charges still end up wasted. You can also shoot it at a vehicle to (try to) deal a glancing hit, whoop dee do. White Dwarf plays it up as the Tyranids' "psychic sniper", and it's so hilariously inept at it that you wonder how the Hive Mind is still a threat at this point.
It's a damn shame, because in the fluff it is described as an absolute rape machine, with broods of them able to go up against Mephiston and make him look silly.
Eighth Edition
And then came 8th edition, and everything changed. The Maleceptor has now become something of a miniature psychic powerhouse. It won't win any games on its own, but it can catch an unprepared opponent by surprise.
Statistically, The Maleceptor packs a surprising amount of durability into its frame. toughness 7 with 12 wounds, a 3+ armor save and a 4+ invulnerable save gives it the same level of durability as a Hive Tyrant. On top of that, it knows the same number of psychic powers, and adds 1 to all its psychic tests. This really shines when it comes to using smite as you will be getting multiple mortal wounds more reliably.
In addition, its psychic overload ability is still around, but now hitting up to 6 units within 6" until at half wounds and going down from there. To add to the new reliable goodness there is no roll to manifest Psychic Overload, 6 units within 6" get slapped with a mortal wound on a 2+ and THREE on a 6.
Melee wise, it will only be hitting on 4+ with 3 attacks, but those Massive Scything Talons are no joke. Doing D6 damage at -3 ap and rerolling hit rolls of 1, the Maleceptor has become the Rape machine he was hyped up to be. Gee, looks like that's two shitty Tyranid units we've seen with a comeback thanks to 8th edition!
Ninth Edition
In 9th edition, the Maleceptor fits well into its new role of a heavy supportive psyker with a bomb hidden in its pockets. It's received a boost to its durability since 8th edition with 3 more wounds and toughness 8, it moves an extra inch and its WS/BS has been improved to a 3+ alongside its scything talons becoming a fair bit nastier, sporting two weapon profiles where one has high strength and single-hit damage whilst the other doubles the attacks you can make. The real meat of its update is in its reworked psychic abilities: instead of choosing not to use psychic powers, the psychic overload ability simply deals 3 mortal wounds, which degrades when the Maleceptor is damaged, to the closest enemy unit within 12" if the result of a psychic test or psychic action is a 7+. Whilst the Maleceptor doesn't get a +1 to its psychic tests anymore, the ability is nowhere near as swingy as it used to be, is much more likely to reach its full potential (Seriously, how many times has your opponent put SIX units within 6" of a Maleceptor?) and, most importantly, doesn't require you to forgo all of your other psychic powers.
The Maleceptor has also received an interesting new ability, previously a stratagem from Psychic Awakening. Instead of using any psychic powers, it can opt to try and perform a psychic action with a warp charge of 6. If successful, it gains a 6" aura until the start of your next psychic phase that reduces the strength of enemy ranged attacks targeting units within the aura by 1. This can provide much appreciated boosts in toughness to a lot of Tyranid units and can make even Termagants annoying to shift or you could be a little cheeky and run around with effective toughness 9 monsters in your army. This big brain bug has come a pretty long way way since seventh edition and is now equally happy to provide forcefields to your army or to peel open dreadnoughts like cans of tuna.