On deop
From Scriptwiki
The on DEOP event triggers when a user on a channel is deopped.
on <level>:DEOP:<#[,#]>:<commands>
$opnick refers to the user who was deoped.
Example
Triggers when a user with level owner was deopped in #help.script or #mIRC and ops him again:
on owner:DEOP:#help.script,#mIRC: { mode $chan +o $opnick }
See Also
On op triggers when a user was opped.