That said, even without upgrades, these things are holy terrors, especially against any vehicle with AV12 or worse and especially against Flyers. Take three of them, put them on a Skyshield Landing Pad for improved LOS (i.e. due to height) and a 4++ save and they can reliably take out 2-3 enemy transports a turn or, if they stand still, they can choose to have Skyfire and Interceptor and take out 2-3 incoming flyers a turn before the flyers even get a chance to move, shoot, or drop off troops. To prove this, let’s crunch some numbers:
-Against AV10 vehicles (like very light Flyers, Marine Land Speeders, Sentinels, Dark Eldar Skimmers of all kinds, Ork Trukks, etc.) each Deredeo will have 4 shots, likely 4 hits (BS5 Twin-linked means a 97% hit ratio) and an average of about 3-4 glancing/penetrating hits (i.e. S8 vs AV10, with re-rolls from Sunder special rules, means 2+ to glance, 3+ to penetrate, all with re-rolls)… that basically means, not counting any kind of Invul or Cover saves, one dead vehicle per Deredeo… in 2-3 turns of shooting, these 3 Deredeo Dreads can completely “demech” an opposing army all by themselves, leaving the rest of your force free to move, shoot, and assault unmolested.
-Against AV11 vehicles (like Rhinos, Immolators, Tauroxes, Devilfish from the sides, light flyers, Necron Vehicles with their Quantum Shielding gone, etc.) each Deredeo will likely get 4 hits and an average of about 3 glancing/penetrating hits (i.e. needing 3+s to at least glance, 4+s to penetrate, with re-rolls from Sunder), so that will kill most of these vehicles outright, again letting you taking out three transports/light tanks/light flyers every single turn.
-Against AV12 vehicles (like Chimeras and Devilfish from the front, Wave Serpents, Heavy Flyers, and almost all Eldar Grav Tanks), each Deredeo will likely get 4 hits and about 2-3 glances/penetrations, meaning that you can reliably down about 2 AV12 enemy vehicles a turn with your 3 Heavy Support Deredeos (you can use the rest of your army to make that 3-4 dead AV12 vehicles a turn, if you have some additional long-range shooting to support the Deredeos). This is especially useful against deadly flyers like Stormravens or Stormfangs or Heldrakes, since the Deredeos can use Intercept to neutralize them before they even can contribute to the battle (and neutralize any squads they happen to be carrying).