This next stage will require more research, a tripwire and Vinculum. If you have not scanned Vinculum yet, then scan a door or a gate.
Just like Projectile or Bolt, this will be your first modifier. You can set the target type to either friendly or hostile. When combined with an element like fire or earth, it will allow you to throw down mines that will explode when friendly (or unfriendly) mobs walk over them. When mines explode, the AOE effect will damage any mobs nearby (including mobs not targeted by the mine).
These can do a lot of damage and they take around two seconds to activate when you first drop them down.