Silver Griffon
Explorer
I think tumbling past the dragon is perfectly OK.
Here's why (Please read carefully. I know the dragon in question is only 1 or 2 sizes larger than most PC races. The point is in bold text.): Any character can move through a space occupied by a creature three or more sizes larger than itself. (I believe this is in the Player's Handbook under Movement and Position/Tactical Movement/Passing Through. AoO applies without tumble, of course.) This is because most creatures do not take up the entire area of the sqaures they occupy (gelatinous cubes excepted
). I don't see any reason why a trained Tumbler of small or medium size couldn't do the same thing with a size large dragon. A narrow corridor actually makes this easier for a "Jackie Chan" type who can make use of the walls to tumble off of and/or climb/run up them. Heck, he could even tumble on the dragon's body as he passes!
I do agree that the difficulty of avoiding AoOs should scale against the opponent in some way, though. I like the Ref save to avoid losing your AoO if someone tries to tumble past you.
Here's why (Please read carefully. I know the dragon in question is only 1 or 2 sizes larger than most PC races. The point is in bold text.): Any character can move through a space occupied by a creature three or more sizes larger than itself. (I believe this is in the Player's Handbook under Movement and Position/Tactical Movement/Passing Through. AoO applies without tumble, of course.) This is because most creatures do not take up the entire area of the sqaures they occupy (gelatinous cubes excepted


I do agree that the difficulty of avoiding AoOs should scale against the opponent in some way, though. I like the Ref save to avoid losing your AoO if someone tries to tumble past you.