Since Destiny's launch, one thing has been clear: Warlocks are strong. Really strong.
Whether it's the ultimate ability of the Stormcaller subclass or the Sunsinger subclass' ability to return users back to life, Warlocks are powerful in both Destiny's PvP and PvE activities. It's for that reason the April Destiny update will be bringing some fairly big changes to the various Warlock subclasses.
Sunsinger Warlocks are probably seeing the biggest change. The amount of shield granted by their Scorch melee is being reduced, as is the amount of time Radiance lasts if you use it to resurrect from beyond the grave.
On the Stormcaller side of things, players can expect the Landfall ability to be taken down a notch. This perk for the Stormcaller ultimate causes a massive bolt of lightning to strike the ground when activating your ultimate, often to devastating effects. Using the ability's lightning attack will reduce the super meter faster than before, and perks that prolong the length of the ultimate are also being adjusted.
Bungie hasn't detailed all of the exact changes just yet, but that should give Warlock players plenty to chew on. As for everybody else, a number of Crucible and weapon changes are coming in the April update as well. Revives will take longer in PvP, and players will have to be closer to their target to activate a revive. Players will spawn with special ammo, with a special ammo crate then spawning three minutes into the match. Players should expect to receive more legendary drops in Crucible, and for those playing during the Iron Banner, legendary drops will be replaced with Iron Banner gear.
All of the game's weapon types will see various tweaks. Hand Cannons will have increased ammo capacity, high rate of fire Auto Rifles are being nerfed while low rate of fire rifles are being buffed, Fusion Rifles are getting some additional stability and Sniper Rifles are getting a hit to stability, while also taking longer to scope. Low rate of fire Pulse Rifles will see a slight damage increase. Across the board, heavy weapons, sniper rifles and shotguns are getting reduced ammo capacity.
In addition to broad weapon changes, a number of legendary and exotic weapons will see changes as well. Suros Regime is getting a slight damage buff, the 100-Yard Stare (apparently the most equipped special weapon in Destiny) is having its ammo reduced (as is Quillim's Terminus). Last Word is getting a nerf to its last shot damage bonus, while Hawkmoon is getting a nerf in the form of better range and accuracy.
Bungie will detail a more definitive list of changes tomorrow, but the above seems to be the major points to come out of the developer's Twitch stream. You can read more about Destiny's upcoming April 12 update here.