Pre-Forsaken dev video (combat stream I believe) confirmed ability mods will stack up to 5 times. With 3 mods pre-forsaken being equal to 3 mods post-forsaken. The issue is less the mods stacking with themselves and more them not stacking with other forms of ability regen. It’s also inconsistent based on the exotics. For example: Frost-E5s (I think that’s right?) stacks with mods to lower your dodge roll as low as a 6 second cooldown with 3 mods (possibly lower with 5 paragon mods) Crown of Tempests caps after 2 mods. This can be seen as 3 melee mods and 2 grenades on the bottom sub tree of stormcaller (with the lowest melee cooldown), both melee and Grenade regen at the same speed to the same amount. Even though Grenades have a 1:15ish? Cooldown and the bottom tree melee has a much lower cooldown (45sec if I remember correctly) without mods. Haven’t even tested Super Regen mods with Crown of Tempests yet. Hallowfire Heart for Titan, running the bottom tree with sunspots, with your ultimate charged. Running 3 Grenade mods, the cooldown while standing in a sunspot is barely faster than the cooldown when not. Which means the ability regen caps out before the sum of Hallowfire Heart, mods and Sunspots. Benevolent Dawn perk on Well of Radiance caps out at what appears to be 1 mod. With no mods regenerating 1/2 of all your abilities, and 2/3 with 1 mod, any more and regen speed is unaffected. Nezarec appears to cap at 3 mods, as grenade regen is still roughly 7-8 seconds with 5 mods, same as pre-forsaken with 3 void ordinance mods. Certain exotics and abilities also completely ignore ability cooldown, for example, Empowered Starfire Protocol, Young Ahamkara’s Spine, Arc Titan Shoulder Charge all provide fixed amounts of ability energy when they proc. The pattern that’s emerging is if you want ability regen, stacking mods is a waste of time and you need to run certain exotics instead. Or run 5 mods and a combat exotic like Wormhusk or Ophidian Aspect, and only have 1 ability available every 25-30 seconds. As opposed to the glory days of D1 Warlock with self refunding void grenades, 7 sec melees on Radiance or Perpetual Charge, no exotic required.