headhunter's mark - ideas needed

[mirrorman1de]

i created a spell that searches the the enemy unit with the highest level in the proximity of the triggering unit and puts a headhunter's mark on it.

the unit is visible to its enemies and has a reduced armor. in addition, when killed it spawns 250 gold.

i want that ability to be an ultimate but for now it is too weak.
i thought about a mechanism that changes ownership of a random ally unit of the unit with hunter's mark which is the traitor who sold out the hunted unit ....

any ideas? map is AoS type.

 

[Dirac]

Increase the damage done to marked units in 30%?

 

[Dinowc]

Make your allies invisible (including the caster) when you are close to the marked unit so you can ambush him

 

[Vylatin]

Slow the unit's movement speed too. Then it will be both easy to find him and catch him! :thup:

 

[Man-o-Bomb]

What about creating illusions of the headhunter once in a while around the target, so he thinks he gets attacked all the time?
(Could be really cool if they always spawned out of hes vision and then run in to attack)