In my own experience, limiting telekinesis tends to be mostly inconsequential, finding the loopholes that allow you to work around said limitations without a noticeable drop in power, is relatively easy. Telekinesis is one of the easier powers to abuse. Primarily because unlike other similar "Manipulation at a distance" powers, there is no stipulation on what they can manipulate. Compare Pyrokinetics -Pyro for fire, Kinetics for movement- which tells you precisely what the scope of the power is (within limits, remember this is still a fantastical ability) Now Telekinetic, -Tele, for Far off, or at a distance, and kinetics again. The prefix of "Tele" is almost redundant when using it to talk about powers. [nuffsaid] What you are left with is just Kinesis/Kinetics, ergo: movement, or momentum, whatever you'd like to call this for your own comprehension. Sounds very close to something called physics, which is the scientific study of matter and movements. So a Telekinetic is someone's whose ability is to manipulate movement/momentum. For anyone who has seen A Certain Magical Index, or A Certain Scientific Railgun, you see where I'm going with this.
So you decide to prevent them from manipulating biological organisms, for the obvious reason that without this limitation, or providing other characters with a suitable defense, a Telekinetic can essentially kill anything within range. Of course this doesn't prevent the Telekinist from causing your shirt to constrict around your neck, effectively choking the life out of you, or perhaps he removes your gun from its holster, before blowing your brains out. Alright so we'll limit how massive an object he can manipulate. Perfectly reasonable, though once again, the loopholes are easy to find, needles through the eyes, or drown the man in dirt/sand, etc etc. Hell, you could theoretically create a Vacuum around someone's head, which would have very obvious and immediate results, or compress the air around said person's head until the pressure made them go
POP . Another commonly ignored problem is that Telekinesis essentially provides a limitless number of auxiliary powers for those adequately educated. Pyromancy, Check. Aquamancy? Check. Geomancy, Check. Necromancy (providing the previous no biological matter rule hasn't been applied) Check. Flight, superstrength, invulnerability really I could continue this as long as I want, almost every single power can be derived from Telekinesis, (Or it's sister, Telepathy) with the proper approach, excluding ones that essentially entail creating something out of nothing, and with sufficient explanation, Telekinesis could easily accomplish this as well.
I've got it, we'll make it so that using Telekinesis tires the character out. This is probably the only check which can actually work, provided the setting allows non, and even then it's rare. Mental exhaustion, or physical? Perhaps some other source altogether? Exhaustion is a nice limiter, but it doesn't actually prevent any abuses, merely allows for them to be spaced out more, Just because floating that belt of grenades into the barracks (Honestly, in the proper setting this is hardly Telekinetic abuse, just smart thinking, but bear with me) leaves Anita with a nosebleed and a migraine, or even completely burnt out, doesn't change the fact that once she recharges her batteries, she will be just as powerful as she was before (Perhaps more so if this is the type of Telekinesis that is developed over time)
"Spooki, your being excessive, if she gets tired out from lugging a belt of grenades only 300 feet or so, and can only do it once a day or so, provided she can't use her power on organics, and avoids the 'loopholes' you just described, whats to stop said character from being a valued contributor to our team/story?"
Firstly, I want to take this moment to say I'm not implying that
@RokkuHoshi will not be a valued member of the RP, or a contributor to the story/team. Or that I think he is going to try and abuse his powers to the limits he is provided. I'm only mentioning my own reservations regarding Telekinesis as a mutation, and fully understand if either Penguin or Potter takes no issue with it, and also this isn't raising any objections to Pyrokinesis/Aquamancy/Geo etc etc, though those do lend to certain abuses as well.
The second part is that the entire problem is that once you provide a solid "Level" of power for the Telekinetic to work with, you begin to be able to figure out what all the loopholes are. Assuming (pulling out of my ass) the grenade belt had 8 grenades, and each grenade weighs roughly 1 pound, with the manipulation of the belt being at 300ft, that gives us 8lbs @ 300ft or in other words the power to manipulate a m16 from 100m away. Without adequate preparation, or awareness, this is a death sentence for any opponent. Compare that to a Pyrokinetist, who, assuming the same range and a relatively similar power in terms of scale (unable to turn entire cities into ash with the flick of a finger) any opponent while still at a Disadvantage, mainly has to guard against burns, smoke inhalation, and perhaps a few more excited reactions. In contrast, fighting against a telekinetic by definition implies you must guard against almost the entirety of the physical realm.
(Wth is wrong with me....)