Charm monster is generally considered too powerful and too low-level, and should probably be nerfed. Ideas:

• It only works if you’re not wearing any armor. (This is apparently how D&D does it.) Alternatively, its chance of successfully charming is reduced the more armor you’re wearing.
• Make it more reliable than it is now, but it always fails if you have other pets. (You can then only have one pet at a time without using scrolls of taming.)
• It only tames one monster at a time. (Make it a directional beam with a maximum range of 1.)
• It only pacifies monsters, and can’t be used to tame an always-hostile monster.
• Make it do what the temporary pet code in the Bard patch does: the monster remains tame for a fairly short amount of time and then reverts to whatever it was originally.
• Split into three spells: pacify monster (peaceful for charisma*2 turns), charm monster (tame for Charisma*2 turns), and dominate monster (tame permanently or for a long time).
• It only works on monsters, and doesn’t work on intelligent beings.
• It can’t directly tame a hostile monster; it can only pacify it. Peaceful monsters can then be tamed by subsequent casts, but attempting to tame a peaceful intelligent monster may anger it instead. The pacification step is dependent only on monster MR, but the taming depends on the player’s level relative to the target. The scroll of taming should remain comparatively powerful.
• Scale with skill: unskilled attempts to pacify one adjacent monster, basic to pacify all adjacent, skilled to tame one adjacent, and expert to tame all adjacent. All of these are subject to normal monster MR checks.
• Whatever nerfs do get applied, they should ensure that the scroll of taming is more powerful and reliable than the spell.

Some ways to scale some spell effects with skill. Generally, this consists of nerfing unskilled and basic casting rather than adding even more powerful high-skill effects.

• Beam spells such as knock and wizard lock scale the range of their beam with skill, with only a few squares at Unskilled, up to 4 squares at Basic, up to 6 at Skilled.
• Identify always identifies exactly 1 item when Unskilled.
• Light scales its radius with skill.
• Charm monster only pacifies 1 monster at Unskilled, and can only tame 1 monster at Basic, 3 at Skilled, no cap at Expert.

High level spellcasting monsters should have stone-to-flesh in their arsenal. Then they can use it on statues which come to life, always fighting on their side. They should also attempt to cast charm monster on your pets, with success inversely proportional to the pet’s level.