Hi all,

Quick question here. Does anybody remember a class or monster ability that allows a creature to push an enemy, then immediately enter the space vacated by that creature? I seem to remember seeing something like that, but I can't remember where. Thanks!

Everyone should be able to do that, per the rules p190 of the PHB, see "Breaking up your move" and "moving between attacks".

You should be able to move, shove someone, and then move again (provided you have movement left), then even attack again, if you have Extra Attack.

Maybe there's a (sub)class that has a feature specific to it, but it seems like a waste.

Wow. This should have been shockingly obvious. I think I had my head too far in 3e world, where breaking up a move was a 3+ feat investment. Thanks!

You might want to look the Shieldmaster feat.  Loads of fun there.

Yeah. I was pretty sure I was thinking of some monk or fighter ability. Then I remembered that what I had in mind was a combination of a feat from 3.5, and a fighter power from 4e:

SUN SCHOOL [TACTICAL] (3.5e Complete Warrior)
You have learned a number of esoteric martial arts techniques inspired by the sun.

[SNIP]

Inexorable Progress of Dawn: To use this maneuver, you must hit the same foe with the first two unarmed attacks from a flurry of blows. If you do, your foe must move back 5 feet, and you may move 5 feet forward if you wish. This movement does not provoke an attack of opportunity for either character.

Tide of Iron (4e Player's Handbook)
After each mighty swing, you bring your shield to bear and use it to push your enemy back.

[SNIP]

Hit: 1[W] + Strength modifier damage, and you push the target 1 square if it is your size, smaller than you, or one size category larger. You can shift into the space that the target occupied.