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  * cast summon demon
  * cast control demon onto the intended target

1. too short a radius: control demon's target must be quite close to the demon - chances are the demon will score a few hits before you can bind it to a target. This leads to a strange dance wherein the player attempts to lure the demon towards the target while avoiding damage from both the target and the demon.
2. notification: the target reticule should notify the player if the target is byeond the spell's radius
3. priorities: control demon assigns a lower attack priority to the target than the summoner. If the target and summoner are lined equidistant from the demon, the demon will invariably attack the summoner. If the summoner is between the target and demon, the demon will of course attack the summoner. Ideally the summoner will not be attacked while demon has been bound to a living target.
4. undead: doesn't work with undead - fallen undead are ignored by the demon even after they rise again. Ideally once fallen the demon will move on to the next target (usually the summoner) until previous target rises again, after which it will then return to the rerisen undead.
5. multiple targets: multiple attack targets should be supported. The demon should move to the next target in the queue once the current target is dead/fallen.