SC2Mapster

I think he has applied a spawn behavior of the hatchery to spawn larvae.

For the larvae to hit a unit they need a weapon eg baneling.

Larvae that are spawned wont automatically target the target of your hybrid. For that you are better off using an Arm Magazine ability with units set to external.

You could try using the Texture Select By Id (used by some protoss buildings) actor event to reskin some ripple or the xelnaga field effect (with z adjusted) combined with the creation of a Terrain Deformer (used by buildings usually to flatten where they are built). You could also use a Mover to raise its height a little (like automated refinery text kicker) and give the actor the Shadow SOp so it follows your hybrid to create the visuals of the effects of the ability.

You will need a Unit Compare Field validator (like the Is Flying one) to compare the height of the target relative to your hybrid. Have a Behavior type ability so you can activate/deactivate it and give the applied Buff behavior a periodic Create Persistant effect. For the create persistant effect give it various Search Area effects of an increasing radius (make sure to set the filters right) with the Search - Areas - Effect linking either to an Apply Behavior or create periodic effect. The apply behavior could apply a buff to the targets for a set duration giving -ve hp regen to damage them or periodically applies a damage effect to them. With the other create persistant just get it to apply every so many secs to the target doing a damage effect.