The conversations on my blog about shield and armor talents has brought up spell resistance. If it’s in the game, one or the other of these talents would be an appropriate mechanism for gaining it.
However, I have to wonder… is Spell Resistance really an appropriate mechanic in the first place? It largely amounts to a little sign that says “you must be at least *this* tall to cast against this monster”. While I admit I am okay with things that limit spell casters (because non-casters need something they can deal with better… though the orb spells take even that away), is this really a valid mechanism for Echelon? Or D&D in general, come to that?
We already have mechanisms for avoiding effects: saving throws and armor class. Might a better solution than a straight level check be to simply have spell resistance grant a bonus to saving throws and armor class (for those spells that have attack rolls but no saving throw)?
What effect would this cause? As far as I can see, it still means that a creature with SR is harder to affect with magic. Almost all spells that can have negative effects have at least one of an attack roll and a saving throw (slay living requires both a melee touch attack and a saving throw for partial effect) — and I say ‘almost all’ because while I can’t think of any exceptions, I am certain that if I say none people will start shouting them out.
It also means that SR now automatically improves with level. Instead of having a calculation such as “11 + character level” (or some other formula that hopefully comes close to that, since SR equal to character level is nearly useless), you now just have “+2 Spell Resistance”, much as some (many) undead in RAW have Turn Resistance. It improves with level automatically now because it is in addition to other defenses that improve with level, rather than a seperate effect that has be developed.
I just realized, this also means that we can now rationally stack SR, for those who want to be able to stack things (Echelon tries to avoid stacking as much as possible). Instead of trying to find a mechanism for combining SR that takes into account the scaling requirement by level, you just add them together. +2 SR from a magic item, +3 for race, you get +5 on your saves and armor class against spells and spell-like effects that consider SR.
This does mean that conjuration (creation) spells, possibly among others, are slightly weakened. This change, assuming we drop the “Spell Resistance” applicability on such spells, means that spells such as acid arrow no longer bypass SR and become less effective against creatures with SR. I am not certain this is a downside, to be honest; the simplification of the rule may be worth it.
However, it is simple enough to keep the flag and only apply the SR bonus to…
… SR bonus. This mechanism could even be used for creatures unusually susceptible to magic. I don’t know if this is relevant or useful, but I’ll want to think about it.
Anyway. It would be simple enough to keep the ‘SR applies’ flag on the spells and only apply SR on those spells that are not affected by SR, so the previous point about conjuration becoming slightly weaker compared to evocation might not be important.