Na verdade, existe um caminho Paragon que pode ajudar com isso. Especificamente, seu poder de utilidade "Ride the Giant Down":
Ride the Giant Down
Daily ✦ Martial
Move Action Melee 1
Target: One Large or larger creature
Effect: You move into the target’s space, provoking opportunity attacks as normal. Until you leave the target’s space, the target grants combat advantage to you and your allies and takes a –2 penalty to attack rolls, and you grant combat advantage to other enemies. Any attack that damages you also deals half the attack’s damage to the target. When the target moves, you move with it, staying in the same portion of the target’s space.
If the target hits you with a melee attack, it can slide you 1 square to a square adjacent to its space unless you succeed on a saving throw.
Special: if you are trained in Athletics, you don't grant combat advantage to other enemies because of being in the targets space, and you can make a saving throw to negate any pull, push, or slide that would move you out of the targets space.
Esta é a potência do utilitário de nível 12 do Paragon Path Giantslayer .
Esta pode não ser a correção que você está procurando, mas eu pensei em mencioná-la.