ToME: the Tales of Maj'Eyal

I'm playing a summoner, currently level 32. I have a level 28 hydra with 37% hp that refuses to go away. It isn't actually there on screen fighting, it's just taking up a summon slot. It's not a huge deal for now as I haven't needed the 4th slot it's eating up, but I'm just waiting til I do need it and it causes my death. I can't switch spots or explode it as they both seem to require on screen targeting. I did die once and it came back with me. Is there any way to get rid of it?
Thanks in advance,
Harmless

Well, problem solved I guess.

Poor Silk met his demise in orc caves, thus ending the phantom hydra's existence.