We always have rulings in play. It's the nature of tabletop RPGs. Here are two and a musing on a should-have ruling from last session.
Can you pick up and carry someone without breaking their Concentration? No. Just no.
I would let someone Levitate someone who is Concentrating, but to move the person you need to Concentrate, so it's not an effective way to get a Move 3 flying guy to use True Faith with Turning while the party runs along at 3. The caster will be limited to Step.
No, I'm not allowing some wacky explanation of Riding (Barbarian) as a skill so you can do this with a roll. It's just a no.
All I came up with for the 18 Gerry rolled for Invisibility was increased odds of monsters attacking, and then had them attack him as if he'd put some kind of Visibility spell on himself. Even that came up after I drew a blank and then Gerry rolled two really freaking lame effects on the Critical Failure Table, none of which would have been a problem unless he was one second from being brained by surprise from behind. Even then, it would have been no worse than just failing.
So I came up with the Visibility spin.
But honestly, I should have done better. A perk-level Distinguishing Feature (Translucence) would have done - Gerry is mildly translucent for a while after using his Invisibility spell. Not enough for any positive effect, but just enough to make him seem disturbingly unreal, like a bad CGI character, for a duration as long as he was invisible. Not scary - it's not Terror - but more like a situational "-1 reactions you want to be positive because the mage is weird." Heh.
I may still do this* instead of the increased odds of attracting random monster attacks he's got on him now. After all, he rolled an 18 and has Weirdness Magnet. Right now, he's just getting the bounce going against him when it's an even shot of monsters showing up. That's nice but it's extremely minor. The critical failures rolled by other mages with Weirdness Magnet have created monsters (often especially hostile to them), floating mana changes - temporary or not, caused weird reversed effects, alerted mana-sensitive monsters to their presence in a wide radius . . . and I never tell people which of these have happened until they encounter it, and I don't always tie it back to the original event. I probably should, though. It's 15 points worth of the world doing weird - not cute, not fun - stuff to you. It's Unluckiness with -5 worth of supernatural effects tied to it.
Right now I think people see Weirdness Magnet at -15 and think it's an easy choice that offloads work onto the GM and doesn't really cause 15 points worth of issues. I should remedy that impression.
Maybe I just have . . .
* I have done delayed effects in the past - an 18 on Continual Light a few sessions back caused every subsequent stone the caster made for the next few hours be flawed so they'd all extinguish at the worst possible time. Which they did. Still further back an 18 on a Seek-type spell gave wrong information repeatedly to the caster, so the original failure wasn't simply triangulated or tested away with an extra casting. so maybe Gerry will flicker a bit for a while after he re-appears.
If you heal yourself with a damage-healing spell, you suffer a penalty equal to the injury you have. So what about Regeneration and the like? If you go for -1 x the injury that caused the original problem, you end up with a HP 10 guy suffers a -6 to self-Restoration his arm, and a HP 16 guy suffers a -9.
A flat penalty would probably make more sense - a HP 10 person would give a -4 for an extremity to heal the injury, -6 for a limb. That seems pretty fair for a self-healing penalty for all, regardless of their HP. Things deemed beyond "lost limb" (Casting Instant Regeneration to counter an Evisceration spell that took out your kidney or something) would probably be in the -7 to -10 range. One try. Usual rules for critically failing healing spells (Magic, p. 88).
I don't care if you healed the HP or not. Or rather, I do, but I expect you'll have healed them, otherwise I'd cheerfully apply a penalty for lost HP on top of this to the guy casting it. Those spells fix problems, they don't replace healing, and you are expected to deal with HP of injury and limb replacement separately.
This is, parenthetically, an oddity with HP. You can lop off someone's foot, heal the injury, and they are now a smaller person with identical HP and no foot. So you get guys partly dismembered, they down a few healing potions, and they are full HP but just lack a few limbs. Which is fine, but odd when it's during a game session. Whack, arm off! Heal that injury and you're fine!