Xarlen: I am genuinely confused about your point. Are you defending Harm, or save-or-dies in general? If the former, I disagree. If the latter, that's fine. It's the no-save-and-die part of Harm that bugs me.
IMC, harm stays as written until I am convinced, through play, that it is broken. I think that people who have house-ruled it without experiencing it firsthand are being a bunch of Chicken Littles.
Well, firstly I'd point out that this is flawed logic. If a spell is clearly overpowered (which, to my mind, Harm is) then playtesting it is a waste of time. However, in my case, I did run a campaign with a non-save version of Harm. The party cleric loaded virtually all his higher level slots and any combat turned into a Harm-fest.
As for this:
Especially Contingency+Heal.
.
I haven't encountered many 18th level wizard/11th level clerics in a long time.
Anubis: I agree, but I feel you are being too meek. A save for half still makes this potentially incredibly powerful: hitting a 600hp dragon can knock off 300hp with a save. I think that saving for a set amount of damage is reasonable- and in line with other save-or-dies.
LuciusFoxhound: If I were the wizard I'd rather go up against Phantasmal Killer. The cleric can quite often cover the ground quickly, and smack you followed up with a Quickened Inflict Wounds. The only place you're going in the afterlife.
And offhand comments like SR to balance spells is clearly nonsense. By that token, any spell devised could be balanced (with a few very rare exceptions). Firstly, many opponents do not have SR: especially humanoids (yes, they can cast it, but it's easily dispelled). Secondly, SR is a trump card against any spell. Spells have to be compared with other spells of equivalent level, not against SR: otherwise, Power Word: Kill would be balanced with Ray of Frost (both are subject to SR.)
shadracht: Your comments are similar. You talk of magical defenses and such like. But the fact is that magical defenses can trump any spell so it's futile to bring them in. Death Ward can make Power Word: Kill or Wail of the Banshee *less* effective than Ray of Frost. Befuddling the issue with defenses is not constructive.
As for geas, well, yes, the dragon could impose one. And then you could kill the dragon and, the next day, he has to make a Fort save or be sickened. By which time you are dead. The only immediate effect is that oh-so-painful 3d6 damage.