The description of the original helm of teleportation from OD&D recently struck me as particularly interesting:
Helm of Teleportation: The Magic-User employing this helm must have a Teleportation spell in order to take advantage of the device. Having but one such spell the Magic-User can Teleport himself endlessly about the universe, but if he teleports some other person or object the helm does not function and the spell proper is used. Thus the helm is good only to transport the Magic-User himself. Treat as a non-protective helm if worn into combat.
(A passage which also indicates that “protective helms” should have some beneficial effect in combat, but if there’s any explanation for what the benefit would be the rules are rather silent on the matter. I’ve been thinking about applying a -1 AC penalty for missing helmets. But I digress.)
What I was particularly struck by in this passage was the similarity between its mechanical construction and the construction of reserve feats from Complete Mage for 3rd Edition. Conceptually I always liked the idea of reserve feats (allowing spellcasters to make minor magic-based contributions on a regular basis), but found the actual execution to be rather broken. (Allowing wizards to do 6d6 points of area effect damage per round with no saving throw, for example, no longer qualifies as a minor contribution.)
But it might be interesting to take properly balanced reserve-type abilities and have them accessible via magical equipment (like the original helm of teleportation). I’m particularly drawn to the image of magic wands that don’t have charges, but instead allow you to use specific spells you currently have memorized in a powered-down form.
On the other hand, maybe chewing up an equipment slot would be necessary to keep this sort of thing balanced. Or what if there was a percentage chance that you’d lose your reserve spell whenever you triggered the reserve item? In a semi-similar fashion, AD&D’s helm of teleportation limited the number of uses per day based on the number of teleport spells you had prepared. (So that the item extends your magical endurance, but not necessarily limitlessly so.)
Storm Bolt was errata’d to give a save, actually. It might just be a reflection of how we play, I suppose, but a warlock I’m currently playing (variant warlock my DM was nice enough to let me playtest, can use metamagic and reserve feats) has Storm Bolt and basically never uses it. The chance of the enemies making their saves means the damage is low, so I only whip it out for swarms or massive crowds of weaklings.
That said, reserve items are a great idea. Taking an equipment slot seems like sufficient opportunity cost. No need to give them a chance to actually consume the spell (ie. not do their job), I think, that just seems… I dunno, a little punitive.
Cool idea. Item-slot using powers might make sense for a lot of self buffs that aren’t quite good enough to justify the actions required to cast them.
You could also make items that work similarly but actually consume the spell for a longer or more versatile effect (e.g., a crossbow that consumes a use of True Strike to give you a +2 attack for 1 minute/level).
“Helm of Reading Magic and Languages: Wearing this helm allows the person to
read any language or magical writing. It does not protect in the same way as
Magic Armor, so if it is worn in combat any hit upon its wearer should be given a
10% of striking the helm and smashing it.” M&T p37.
Not a clear rule per se, but it must mean that there is always a 10% chance of any hit is to the head when the AC of the head is equivalent to the type of armor being worn. By extension then, there should also be a 10% chance to hit the head and when the heads AC is different – like a plate helm coupled with leather armor – a hit to the head is against the Helmets AC type. If no helmet at all is worn, the strike hits as against AC9.