Honestly... I sincerely dislike this class.
Firstly, of course, it's Psionic Powers are individually discrete spells that you learn and cast same as any other character.
Plus, unlike the wizard, you can only get new ones when you level up or can see another Talent use the power, at which point you can attempt to learn the power as well.
If Talent are rare, then it would be equally rare to find one to learn a power from. And if the Talent
isn't friendly, then you give up your reaction to
attempt to learn the power, which isn't necessarily a smart use of your actions. Wizards can buy a spell scroll or borrow or steal a spellbook, or pull one off a corpse, and they automatically can add the spell to their own book, without failure or expenditure of except of some cash and the time than it takes to transcribe it. Even the weakest psionic power in this system takes more time to learn than it takes for the highest-level spell to be transcribed, and as much as I like the "chance to learn spell" roll from earlier editions and wish it were still part of the game, it's
not.
But
because Talents can also gain powers from taking them, then they aren't a Spells Known kind of caster either. It's a weird mish-mash of ideas here.
Second, building a class from the ground up to nerf itself back into the ground is not a good design for 5e. When a Wizard runs out of spell slots he can still make decent skill checks and not die from using too much magic. The same cannot be said of this class.
Definitely agree. This would probably work OK if
all casters had to make some sort of check to cast spells and/or had to deal with possible backlash. As it is, only the wild mage ever suffers from any sort of backlash, most of which is either instantaneous or lasts 1 minute, and a lot of the time, is fairly benign. Here, strain lasts until you finish a long rest or spend some of a limited resource during a short rest on removing it. And, as you point out, it can
kill you.
It's made worse by Strain being used to perform other effects. At 3rd level, I can charm a target for 1 minute by gaining two Strain (I keep wanting to say
spending two Strain). Awesome. But at 3rd level, I have a grand total of
five Strain. Meanwhile almost every other caster has been able to do the same thing for two levels already, and they don't risk dying (except at the hands of targets who don't like being magically ensorcelled). Plus the other classes that can cast
charm person can do so up to four times per day by third level, whereas the Talent can do it once, spend most or all of their Hit Dice on removing Strain, and can try a second time--assuming they don't fail some of their casting rolls. Which, again, no other caster has to deal with.
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Now, I did take a look at the revised edition, which seems to be mostly a lateral move to me. They've changed it so that there's levels of being tired/fatigued/weary, which feels out of order to me, and puts into mind that OOTS strip where Haley (IIRC) couldn't remember if fatigue or exhaustion was worse. You can still die from Strain, still have to spend HD to remove it during a short rest, and still have to gain/spend Strain to perform other actions.
I don't really feel like being able to have multiple powers active at once, or being able to use powers as often as you want, is enough of a trade-off. It's a class that's going to range from probably OP to literally can kill you, depending entirely on how well you roll.
