No hard rules here.

So I'm trying to visualize it. In 2D, it extends around you in the shape of a square. There's no reason why it shouldn't apply to 3D, so I'm ruling that it expands in the shape of a cube, with you at the center.

The roof is 15 feet above the ground at the edge, so a 3x3 burst should be able to catch creatures on the ground, like so :

Same thing with a blast :

However, large creatures occupy a 2x2 cube, so you could conceivably use that to your advantage.

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Lurker, there has been a rule change to "Throw and Stab". Previously, you are able to throw and stab the same enemy. Now, both targets must be different. Apparently "The power yielded too much damage against a single target."

Additionally, they have removed "charge" from the effect. Instead, you're supposed to move at your speed. There are three implications - you don't get the +1 benefit from charging, but you don't also need to take the direct route to the enemy, or move a minimum of 2 squares anymore. BUT since you no longer charge - and Marauder's Rush only substitutes as a melee basic attack when charging - the combination of Throw and Stab / Marauder's Rush no longer works if rules as written are followed.

I am unsure about one thing - what happens if your throw killed the last enemy in your vicinity, and you want to move towards the others. This was expressly prohibited under charging rules, but no such limitation exists now.

I'm ruling that the pre-errata Throw and Stab remains until you reach level 6. If you'd like to immediately apply the new rules as they are currently written, I'll let you change Marauder's Rush to another ranger level 1 at-will of your choice.

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Shin, you have been affected by the nerf bat as well - thanks to Healer's lore bonus applying only to healing that use surges. Thus, effective immediately, Astral Seal gives 4 HP instead of 9 HP.

What, you don't want my bikini-clad body?