There are immediate action powers where you can attack or follow an enemy moving away, or powers that damage opponents if they move. Could you ally force the enemy to move in order to give you an opportunity to use your power?
...please provide an actual example as it will make it easier to explain.
It depends on the ability.
I'm thinkin' "It depends, but give us an example!" is the best answer from the peanut gallery.It depends.
The specific power on my mind is Booming Blade, swordmage At-Will: the enemy takes damage if it (quote) "is adjacent to you at the start of its turn and moves away".
Could it be that the moving away referenced there must take place during the enemies turn? ( I think a close reading of the text confirms this interpretation.) If so, then forced movement wouldn't be a common option.The specific power on my mind is Booming Blade, swordmage At-Will: the enemy takes damage if it (quote) "is adjacent to you at the start of its turn and moves away".

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.