This sound of this effect reminds of delay, but is smoother and doesn't repeat itself. The pumping reverb is one of the signature sounds of german sound designers Vengeance and is actually quite easy to create.

The effect is made by a normal reverb on a send channel. The reason why to use a send channel is we don't want the original sound to be modified and us being able how much of the effect is blended in to the original.
The trick is to insert a sidechain enabled compressor after the reverb on the send. Control the ducking of the compressor by a 4/4 kick, use a long reverb tail and you'll have that classic Vengeance sound.

The trick of getting a smooth pumping sound is to pay extra attention to the threshold and release parameters. A softer knee and a fast attack might also help getting a nice sucking effect.