"Control" / "possession" Spell

Hi Everybody :) i would like to propose a new spell named "control" or "possession" :

- What makes this spell unique compared to the other spells in the game:
It allows to take control of a single unit or Group of units (best if taking control of a single unit will automatically define it as a leader and therefore all remaining units of the Group will follow it)

- What kind of strategies this new unit would enable (concrete examples are best)
Immagine to attach in "full dragon" mode then casting this spell will allows you to take the control of 1 single dragon promoting it to the leader of the Group. Then using your finger, dragging it on the mobile/tablet screen, you will be able to guide the leader. All remaing units will follow the leader.Once the leader is killed them the spell will be cancelled and the remaining units will be affected by a loss of orientation allowing defence units to overcome them for few seconds.

- How it could combine with other units for more advanced strategies
It could be used on single or Group units changing the strategies

- More features:
In my mind it has to be a "dark" spell and at level 1 allowing to control only 1 unit and at higher levels allowing to control a Group and / or perform different kind of actions.