ToME: the Tales of Maj'Eyal

New ability for summoners: usurp summons.

Passive ability. Any time a creature is summoned within a certain radius of you, there is a chance that you will gain control of it as an ally (i.e. doesn't count to your limit, you can't summon-control it). Radius and chance both increase with level and with willpower.

Replace benevolent spirit, perhaps?

Hum not bad!

It could be sustained, of course, instead of passive. Also, on reflection, I wonder if this would help, or make things worse, since your allies could just provide more targets for summoners to summon at..

Another idea: sustained ability "suppress summoning". Suppresses all summoning in a wide area -- including your own (but anything you've summoned already remains). Would need a short cool-down.

Or perhaps suppress summoning doesn't suppress your own ability, but anything in the area that wants to summon has to make a check against your spell resistance.

Good idea!
Done!