The story so far:
Part of the point of this thread has been not to look at "balance of combat" issues but rather the ability of various abilities to wreak havoc in the quasi-sorta-literary-medievalish setting that is conventional D&D. If every wide spot in the road has someone who can make magic potions, then our sense of reason tells us the world would be very different.
There seem to be two main responses to this basic observation: either change the world or change the rules that would otherwise distort the world. Both are valid and both have advantages and disadvantages.
If you change the world to fit the implications of (at least some of) the rules, then you gain the ease of knowing what the rules are (which shouldn't be underestimated), but, depending on the degree of change, you may have a world that is difficult for players to understand. Also, allowing the rules to dictate the world narrows the range of possible "feels" that you could create in a world.
If you change the rules to fit the type of world that you want, then you have added to the already time-consuming task of world creation the additional burden of coming up with a magic system (unless you opt for not magic at all, which, while "rules clean," does also narrow the possibilities). Many who have attempted to change the rules significantly are trying various "mix and match" approaches, borrowing mechanics from other d20 games and adapting them slightly. Others attempt to create magic systems from the ground up (although only a few of these, at least in my observation, ever reach a stage of polish that would make it easy for someone else to use them).
Looking at Star Wars d20 and Wheel of Time d20, it does seem that manipulation of the magic system seems to be the favorite way to achieve a radically different feel from conventional D&D.
I'll throw out one rule change I've instituted that could possible work outside my homebrew magic system. I have magic item creation call for a sacrifice of hit points (actually, I use the VP/WP system, but it works out about the same). Permanent items require a permanent sacrifice, but it doesn't have to be from the caster. Charged items require a similar sacrifice, but the points can be healed normally. What that change does is make charged items slightly less common, but still available, but makes permanent items (such as swords) very rare. It seems to be the permanent, always on items that cause the most drastic changes in world logic.
Part of the point of this thread has been not to look at "balance of combat" issues but rather the ability of various abilities to wreak havoc in the quasi-sorta-literary-medievalish setting that is conventional D&D. If every wide spot in the road has someone who can make magic potions, then our sense of reason tells us the world would be very different.
There seem to be two main responses to this basic observation: either change the world or change the rules that would otherwise distort the world. Both are valid and both have advantages and disadvantages.
If you change the world to fit the implications of (at least some of) the rules, then you gain the ease of knowing what the rules are (which shouldn't be underestimated), but, depending on the degree of change, you may have a world that is difficult for players to understand. Also, allowing the rules to dictate the world narrows the range of possible "feels" that you could create in a world.
If you change the rules to fit the type of world that you want, then you have added to the already time-consuming task of world creation the additional burden of coming up with a magic system (unless you opt for not magic at all, which, while "rules clean," does also narrow the possibilities). Many who have attempted to change the rules significantly are trying various "mix and match" approaches, borrowing mechanics from other d20 games and adapting them slightly. Others attempt to create magic systems from the ground up (although only a few of these, at least in my observation, ever reach a stage of polish that would make it easy for someone else to use them).
Looking at Star Wars d20 and Wheel of Time d20, it does seem that manipulation of the magic system seems to be the favorite way to achieve a radically different feel from conventional D&D.
I'll throw out one rule change I've instituted that could possible work outside my homebrew magic system. I have magic item creation call for a sacrifice of hit points (actually, I use the VP/WP system, but it works out about the same). Permanent items require a permanent sacrifice, but it doesn't have to be from the caster. Charged items require a similar sacrifice, but the points can be healed normally. What that change does is make charged items slightly less common, but still available, but makes permanent items (such as swords) very rare. It seems to be the permanent, always on items that cause the most drastic changes in world logic.