ToME: the Tales of Maj'Eyal

Target passing in open areas (Abashed Expanse, Temporal Rift, etc...) is too aggressive IMO. In these areas, it is very possible to have nearly every enemy in the entire level swarm you at the entrance because the long unobstructed sightlines allow target passing to reach most mobs. One solution to this would be to restrict target passing to only happen from enemies that can see you. This would restrict target passing to affect enemies up to a maximum range of 20 (with the right setup).

Perhaps there should be some natural errors in the target passing, so that you get a Chinese whispers affect. Up to 4 squares out in either direction for instance. That way the alarm is raised, but it's not as hard to break away and lose them.

If I understand your idea correctly, that wouldn't help at all. Enemies would be drawn to your area from the entire level (in some levels), then target you directly. It would also lead to problems with short range target passing, such as in this situation: With my understanding of your suggestion, the second, third, and fourth enemies would be as likely to move away from the character as towards. With my suggestion, the first two would target you, and the other two wouldn't.