Chain lightning

[Lemming3000]

Im trying to make a game where you take control of units using spells but at the moment i cant make the chain lightning convert all of the units only the first one how can i make it work for all units that are hit.
This is the trigger im using at the moment.
{Events:
Unit - A unit owned by Player 1 (Red) Begins casting an ability
Conditions:
(Ability Being Cast) Equal to Chain Lightning
Actions:
Wait 1.00 seconds
Unit - Change Ownership of (Target of ability being cast) to Player 1 Red and change colour.}

 

[Palaslayer]

read a chain spell tutorial

 

[doom_sheep]

you need to do the bouncing spells all manually