Dunno, the fact that the item isn't consumed is a bit strong IMO. I believe this would lead to Evocation or Necromancy Jars being hoarded on casters and re-cast every 2 minutes for ~free +1 DC.
Question: Can you be affected by Jars from multiple schools at the same time?
Throwing out random ideas... maybe just upgrade the current Draught by making the Jar have 5 charges (instead of 3), and lasting 2 turns like you said. So it would still be a consumable, but an upgrade nonetheless.
Oh, should have noted that only 1 per school can be in inventory / active, to prevent hoarding. Different schools may be used at the same time, yes, as per normal Draughts.
People can already use Draughts like you just described. The reason why they are not, is because Draughts usually are left in the split to be sold, unless they are Divination Draughts required for PWK.
Yeah, looks like u can cs anythin non crit imm. - Big Crit
I can't speak for other players, but I leave Draughts behind simply because I don't put them to use (apart from Divination ones), and gold from selling them has no bearing on that decision. As you said, the option does exist, but for various reasons most players do not currently use them for a consistent DC boost. Having a non-consumable version *would* be used for a consistent DC boost IMO.
Having said that, if more than one of the same school can't be stacked, then maybe... between Limbo SR/Saves it's not easy to land spells effectively at the moment, so maybe +1 DC for a few minutes (6 might be too much?) could be okay.
To me 3x 2 turns per rest is way too much. You could basically have the power active full time. If it was to provide a more convenient option to draughts I would go for something like 5 charges per server reset/12 hours/recharge in workshop. This would allow you to effectively have 5 draughts for a run, which is what you would need for say elite adarus on a run, but would not be viable to skipping a focus and using gsf Aug + item to effectively have full time esf DC. Also poli I would be hesitant to justify DC and spell pen increase based on limbo alone, as it is meant to be caster nasty, and I'm sure starting in some future PL areas will be more caster friendly