There are some interesting comments here. I didn't give all the background. The party had been fighting him, beat him down to where he was near dead, so he teleported away. The party divined his new location, and went after him. This gave him a round to heal up and recast his buffs, but not much else. He was actually a psionic lich, but I was using magic transparency so the antimagic field got him once the party teleported to his new location and attacked. He had had minions, but they all died in the first part of the fight, and it felt cheessy for me to manufacture new minions at his new location after teleporting. So, what I'm looking for is how can a lich fend off antimagic field without minions, and not in his stronghold (that's where they attacked him in the first place, and he had to run).
Responses to indvidual points:
1- Back away from the anitmagic field. He rolled badly on initiative. The cleric moved next to him, then he was grappled before he had a chance to act, so backing away isn't going to happen.
2- Minions. Dead already. Also, I don't think every high level mage should automatically have tons of minions. Sure, most would, but I think some evil mages would hatch nefarious plots in seclusion.
3- Greater planar ally- he's psionic, so that wouldn't help in this particular situation. Also, is there someway he could call his ally while grappled in the antimagic field, if he were a more standard lich?
4- Create a counter to the spell. Sure, some mages could do that, but I certainly can't do that very often or the players would be unhappy. I also couldn't so that on the fly, as that would have been cheese.
5- Traps. Interesting. I'll use that at some point, but it wouldn't have worked here given the circumstances of the lich's teleportation.
6- Surprise and initiative- part of the problem is he rolled poorly on initiative and went after many of the players. I could have cheesed the die roll, but that would have been, well, cheese.
7- Counterspell- See minions, above. It he had some lower level mages hanging out as minions, counterspelling would be a great plan, but his minions were dead, and I'd rather not have every mage have hordes of minions.
8- Illusions- I assume this one's talking about mislead, which under normal circumstances would be a big help assuming nobody has cast true sight or whatever, but illusions can be an important line of defense. Unfortunately, this one was a psionic lich, and had nothing like mislead.
9- Contingency- Interesting idea, but I'm not sure it passes the "would I let my players do that" test. By a strict reading of the rules, it seems legal, though I'm sure some would argue that the mage can't say "avast" out of turn. I think it kind of steps out of the idea of the spell though, but maybe that's just me thinking of how the spell works in Baldur's Gate 2 which is really my only previous experience with high level D&D play (such as it is). Hmm, as I think about it, I think I'd let me players do that, so it's fair game for the bad guys (or good guys, since in this case the players are evil). Still, that wouldn't help if the lich didn't know there was an antimagic field in play anyway.
10- [added via edit- somehow I forgot this point the first time]- An environment where the lich can survive without magic, but the players can't. That's a great idea, and I'll use it at some point. Unfortunately, this time, they used scry first, then announced the antimagic field plan, so I couldn't say "hey wait, did I say he was in a normal looking house? I really meant he's at the bottom of the ocean." Next time, though, good plan.
Well, I've gotten some great food for thought for next time. I couldn't think of any grand plot to foil the antimagic field in the couple minutes I had, so it worked and the lich got whacked. Fortunately, they couldn't find his phylactery though.