Fallen Glimmer Event: You must destroy all 3 glimmer nodes. If you're shooting a node and it's showing damage numbers, that's probably it.
Fallen Ether Event: You must destroy all small Servitors that assist the big one.
Spider Tank Event on Titan: You must disable all 3 forcefields by using 6 arc charges, 2 per forcefield.
Witches Ritual Event: You must destroy the 2 shielded crystals by standing on the Hex Circles.
Vex Construction Event: You must activate all 3 Vex plates by standing in them until 100%.
Cabal Extraction: You must destroy the Cabal Thresher ship that patrols the area.
Cabal Injection Rig: You must destroy three vents. The top, middle and bottom vents can all be one shot with Wardcliff coil.
Taken Event: As event spawns, there is one main blight which spawns smaller dome blights to its side. If you step in and out of the smaller blights, you receive a buff blight receding. This allows you to damage main blight, which would otherwise be immune. Deal enough damage to main blight to spawn a new boss "Blightmaker".