Like I previously posted about Possessed Space Marines, Warp Talons are significantly better if they are taken from the Khorne Daemonkin codex. Taking a look at their profile, they have:
-Power Armor, 2 x Lightning Claws, Jump Packs as base equipment
On top of this, they are required to take Mark of Khorne (so they have Rage and Counterattack) and also now have Daemon of Khorne (so they have Furious Charge, Fearless, Fear, and a 5++ “stock”). Finally, they have the Blood for the Blood God (BftBG) rule, allowing them to benefit from spending Blood Tithe points.
Put all that together and you now have a fast-moving (12″ Jump Pack Infantry) unit with 4 x S5 AP3 Shred attacks on the charge, all backed by 3+/5++, Fear (to possibly reduce the enemy to WS1) and Fearless (removing one of the key issues of most CSM units, their lack of ATSKNF).
Better yet, you have multiple options to “force multiply” them, including the BftBG (e.g. they can get Adamantium Will, FNP, or +1A, depending on how you spend the Blood Tithe), benefiting from the Herald of Khorne ability to hand out Hatred (the Herald can be on a Juggernaut and join the Warp Talons, or he could ride a Chariot and use the “aura” to project it to them), and even the ability to be buffed by allied Chaos Sorcerers (e.g. Invisibility, Hysterical Frenzy, Cursed Earth, and Endurance all come to mind). Finally, Khorne Daemonkin have access to the Skull Cannon, which can be used to mitigate the Warp Talons lack of Frag Grenades (another critical weakness in the CSM book).
Taken all together, this makes even a minimum 5 man squad of War Talons into quite a threat against anything but models with a 2+ save or heavy vehicles.
For example, 5 Warp Talons with Hatred from a nearby Herald and +1A from BftBG get 26 attacks on the charge —
**Against any medium infantry, ranging from an Ork mob to a MEQ squad, this averages 17-18 unsaved wounds, which is obviously quite devastating
**Against Tau Crises Suit squads, this averages 20-21 unsaved wounds
**Against a Wraithknight, this averages 4-5 unsaved wounds (the S5/Shred on the charge helps A LOT here)
**Against a Stormsurge , this averages 7-8 unsaved wounds (or 3-4 wounds if it has a Shield Generator)
** Against a Hive Tyrant, this unit averages 9-10 wounds
**Against a Rhino, Wave Serpent, or any other vehicle with AV10 rear armor, this generates an average of 7-8 stripped HPs
**Even against a 5 man Terminator squad, this unit averages 2-3 unsaved wounds, just through shear weight of re-rollable S5 attacks, meaning that only 2-3 Terminators will live to strike back on average
Outside of damage output, the Daemonkin Warp Talons can use their above average mobility and survivability (don’t forget about their ability to force Blind tests, potentially reducing enemy BS, their 5++, and the access to FNP via BftBG) to catch agile enemy units (Eldar/DE Jetbikes, Space Marine bikes, Necron Wraiths, and Tau Battlesuits all come to mind) and/or capture Objectives in a Maelstrom game.
Finally, Daemonkin Warp Talons can be taken as part of the “Khorne’s Bloodstorm” formation along with 2-4 Raptor squads and 0-1 Heldrakes, which gives them +1S to their Hammer of Wrath/Vector Strike attacks, making them even better against massed infantry on top of the “normal” benefits described above.
In summary, Daemonkin Warp Talons are still quite expensive points-wise and have vulnerabilities (no Frag Grenades, only 3+ save), but overall they are SIGNFICANTLY better value than the CSM codex counterparts and can be genuinely competitive units with the right employment and force multiplying effects in a Khorne Daemonkin army.