Best way to activate passives?

Best way to activate passives?

I have a passive ability where the hero leaves behind a trail that slows. What is the best way for it to be activated? I used a unit learns an ability. Is there a better way. Also how do I activate it when he dies and is revived?

Create a spell based in any activate spell in the game, Immolation, Windwalk... and then, create a trigger to when a Unit starts the effect of an ability add the passive ability to this hero.

Event
A unit starts the effect of an ability
Conditions:
Ability being cast equal to (The activate spell)
Actions:
Add (the passive skill) to casting unit.

I was unclear, I mean I have an ability that you don't activate and is always on. I want to know what I should use to start effects when he learns the skill or levels it up and what to use to stop the effects when the hero dies.

Also is there a way to get a sight radius higher than 1800?

you should make it so when the hero dies it turns off.

Event-
Unit dies
Condition-
Dying unit equal to HERO_WITH_ABILITY_VAR
Actions-
Turn off ABILITY TRIGGER

then reactivate when he comes back

hmmm to the revive/die thing I don't know if it work but maybe you'll make a dummy ability based off aura selftargeted with no effect and trigger so that ability works when unit has aura's buff.