how to make a poison ability?

how do i make a poison ability that when cast on the target will cause the target to rapidly lose health and move around randomly like its dying a painful death?
and what blue colored object could i attach by special effect to its head so it looks like its face turned blue?

also, this isnt as important but how can i make it take a while to cast it? like it takes a few seconds to apply the poison up close so you would be vunerable for that short period of timetime

Set UnitVarible Targeted unit of ability being cast
Set PlayerVarible to owner of targeted unit of ability being cast
Unit - Change owner of UnitVarible retain color.

For each interger 1 100
If
Life of UnitVarible is greater than 50
Then
Order unit to move to random point in 600 of position of UnitVarible
Set life of UnitVarible to UnitVarible - 50
Else
Unit - Explode UnitVarible
Skip remaining actions
Wait .25

Change Owner of UnitVarible to PlayerVarible

just wondering...is this type of triggers related to how TRUEBasic works?
cause if it is...ima listen in class and actually learn this....

*grumbles*

JASS is indeed slightly similar to Basic, but a lot closer to javascript. (Basic, Not VisualBasic.)

That wont work unless u add this

ok im going try that,
what about attaching a blue colored object so it looks like its face turned blue?
is there a blue unit -missile model or something that i could attach?

also how can i make it take a while to cast it? its a item ability , is there something that effects how long it takes to cast so the poisoner will be vunerable for that short period of time?

EDIT: i just tried it and i cant seem to make the unit move, can u elaborate on the move order? also, what should i change the owner of the poisoned unit to?