Interesting class game mechanic...

[Pyrex]

Swift action?

as in once a round for only the cost of no free action special abilities/spells?

That's a bit closer to spontaneously doing anything you want to than the runes sound like.

Right, a Swift action once/round to redistribute your free incarnum.

However, they aren't spells. You have several different incarnum-sinks (called soulmelds)which can each hold (level dependent) up to 4 or so incarnum. One sink might give you +1AC/pt, another might give you +10'speed/pt, and a third might give +2dam/pt on melee attacks.

 

[Hypersmurf]

Artificer's Handbook has socketed items, like those found in the Diablo games.

You could have a +1 socketed longsword. You can place a rune of fire or a rune of cold into the socket and change the kind of damage the sword does.

Changing out the socket is a move equivalent action.

Armor and shields can have sockets as well.

I quite like the way Fate handles sockets. An item can have one or more sockets; once you place a gem in a socket, you can't remove it. You can, however, destroy a gem to free a socket; alternatively, you can destroy the item to make all its gems available for use once more.

Makes you think about which gems you want to add to which items a bit harder

-Hyp.

 

[DarkKestral]

I quite like the way Fate handles sockets. An item can have one or more sockets; once you place a gem in a socket, you can't remove it. You can, however, destroy a gem to free a socket; alternatively, you can destroy the item to make all its gems available for use once more.

Makes you think about which gems you want to add to which items a bit harder

-Hyp.

Which is precisely how World of Warcraft and other games that have socketed items (it's a common thing in the MMO world) run their socket or socket-esque systems, except with the item destruction bit. (Though if that were added, I could see players forgoing selling their used equipment for cash, if the gems are valuable enough...) Very elegant, actually. Giving the player flexibility in regards to their items' properties while maintaining a rough balance of power between each ability. (as a stronger ability could always cost more or use more sockets..)