Interesting Magical Variation

[JLV]

I was reading through my PDF copies of Fight On! magazine the other day, and ran across this fascinating magical variation:

"Spontaneous Magic: Mages in fantasy fiction often can make many small spells without trouble, yet in many roleplaying games they only have a small-to-middling number of fairly potent spells instead. For GMs who prefer a different approach we offer the following:

Mages should be allowed to extemporize small spells based on their current spell list. Thus a mage who currently has Exploding Orb of Plasmatic Fury
committed to memory could light a candle or campfire without incident; one who has studied a telekinetic dweomer might nudge a box off a mantel; one who can cast Slumber might be able to make someone yawn momentarily; and so on. The possible effects should always do little to nothing directly – certainly no more than one point of damage even in the best of circumstances for example – but player creativity can sometimes give them great indirect effects in play. They also allow your mages to help out in little ways and do the neat tricks that wizards in some books do. As your mage casts the spells on her list, she also gradually loses the ability to create these spontaneous effects, representing the decrease in magical force that working greater enchantments (i.e. ordinary spells) inevitably causes. If you use a mana point system instead of spells that disappear with use, simply have the minor magical effects cost one mana point each instead."

Now, while that's written towards D&D-ish OSR games, clearly we could just as easily substitute TFT spells for the effect. Someone who knows Fireball can light a candle or get a campfire started; someone who knows Magic Fist can nudge that box off the mantle; someone who knows Rope can tie or untie a knot, etc., etc.

Clearly also, we would use the "mana points variation" to determine cost -- though a cost of 1ST might seem a bit high. Still...

This would resolve the debate over cantrips and the like, and make for a much simpler variant of the cantrip idea that could easily be applied. It also allows the players to make an argument for being able to do something tiny (yet sly) that can have an outsize effect on an encounter; e.g., tying the bandit leader's shoelaces together while he tries to terrorize you -- when the fight begins, he has to roll 4/DX to avoid falling down immediately (remember, it's just an example).

Anyway, thoughts anyone?