Creating rules for jumping or climbing onto monsters?

Question

Partly inspired by this thread's discussion about creative role-playing and one answer there referring to stunts, I wanted to adapt a similar concept to the fairly rules-strict D&D 4th Edition.

One of the issues that has often come up in our campaign is jumping onto or climbing onto monsters. For example, when fighting dragons, one of our players has repeatedly expressed a desire to climb onto the dragon's back. However, there are no rules, to my knowledge, for jumping or climbing onto a monster and the rules for mounted combat are limited to willing mounts.

How would you create a set of rules for D&D 4th Edition to cover jumping or climbing onto monsters and holding on to monsters? These rules should cover climbing up giants, leaping onto a dragon's back, or holding on a roc's leg as it flies away.

Answer 1

There is actually a Paragon Path that can help with this. Specifically, its utility power "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.

This is the level 12 utility power from the Giantslayer Paragon Path.

This may not be the fix you are looking for, but I thought I would mention it.

Answer 2

I would base it on the grab action, that puts you in some kind of virtual square on to of the target. Here is my attempt.

Mount: move action

Target: You can attempt to mount a creature that is at least one size category larger than you. The creature must be within your melee reach (don’t count extra reach from a weapon).

Dexterity Attack: Make a Dexterity attack vs. Reflex. Do not add any weapon modifiers. You must have at least one hand free to make a mount attempt. Hit: You have mounted the target. The target provokes combat advantage against you. Your target can attempt to escape on its turn. (phb page 288)

Sustaining a Mount: You sustain a mount as a minor action. You can end a mount as a free action.

Effects that End a Mount: If you are affected by a condition that prevents you from taking opportunity actions (such as dazed, stunned, surprised, or unconscious), you immediately let go of a Mounted enemy. If you move away from the creature you’re Mounting, you let go and the Mount ends. If a pull, a push, or a slide moves you, the Mount ends. In any of these cases, you at least take 1d10 falling damage.

Answer 3

D&D Blogger Zak Snyder came up with an elegant solution, which I'll reproduce here. (The blog is NSFW.)

Attacking big monsters: for every round spent climbing on (not attacking) a big monster without falling or being thrown off, you get +2 to hit and damage for when you do attack while on it. You are also protected from many of the creature's usual attacks depending on where you're climbing and what part of it you're on.

If it tries to throw you off? Save or dex check or whatever the climb mechanic is.

I figure that's the monster's attack, not yours, so holding on isn't an action, but trying to improve your position is.

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Mathwise, this idea is in your favor and better than just hitting from the ground if:

• you're good at climbing (dex) and
• you can manage to stay on there for a long while and keep hitting from the position you get in--skip 2 or 3 rounds of regular to-hit chances in exchange for several rounds of harder hits, and
• the monster's morphology makes it hard to direct its most dangerous attacks where you are

...which should explain why Legolas and the Hobbits climbed up on the cave troll but Aragorn and Boromor didn't bother.

Answer 4

In The acquisitions Incorporated podcasts, DM Chris Perkins sets a DC for climbing onto a Dracolitch. The players then use the rules for doing skill checks in combat to climb onto monsters.