See title.
You place the runes, they need 1,5 seconds to arm, after that they go off when a enemy walks over or are close by to it.
the rune of kalastor however has a small “explosion” when you cast it on the ground to stun enemies (it also needs 1.5 seconds to arm) and will go of when a enemy walks over or are close by to it.
hope this explains it?
Like Arcane Bomb devotion skill ?
yep
10/char