I wanted to ask about converting some 3.x spell mechanics to 4e, particularly the concepts of “caster level” and “saving throws”. As a caveat, I should say I only played maybe 3 games of 3.5 before 4e came out, so most of my understanding is based on reading the rulebooks, not how things actually played out. Please pardon my thinking out loud.
Caster level seems to mostly affect how “big” the spell is – either lengthens duration, makes more of the effect (ie number of Magic Missiles), or otherwise increases it in some way. Increasing your caster level just changed your starting point on a sliding scale of effect. But 4e spell mechanics don’t really have durations other than “save ends”, and if you want a bigger AoE you take a feat to do that. So to phrase this as a question with a particular example, if there was a 3.x ability that says “Add +2 to the effective caster level of the spell”, what does that mean in 4e terms?
And the same question for saving throws against spells. As I understand it, it’s basically the “to hit” mechanic, only reversed from 4e. In 4e, the attacker rolls to hit, while in 3.x the target rolls to not get hit. Either way, both are hoping to roll high to determine whether an attack lands or not. So if a 3.x ability says “Add +2 to the DC to the spell save”, you are making it harder for the monster to roll it’s save by 2 – the 4e equivalent of lowering its target defense by 2. Am I interpreting this correctly, that a save vs spell at +2 is the same as an attack at -2?
For the curious, the reason I’m asking is that I’m trying to convert a 3.5 FR gem mage to a 4e character. The basic schtick is that for an additional cost, you can include a particular sort of gem in the creation of a magic item, which enhances the item’s properties (the sort/amount of enhancement varies with gem type). For instance, if you use a 5000gp Ruby in the item, it raises the save throw to any evocation spell you cast by +2, or if no save allowed, raises the effective caster level by +2. I’m wondering what that means in 4e terms, because if my interpretations above are correct, for a 5K extra investment, I can get a permanent +2 to [insert keyword] attacks and/or some other effect boost. That seems pretty powerful…?
Any input or insight would be much appreciated, thanks!