when you load up the revs it stops the cyclic idle as its name suggests it only effects the idle, when you get into the antilag areas it adds more fuel, reduces the ignition timing massively and doesnt fire on all cyls so you essentialy are firing the cyl into the exhaust manifold on some and putting raw fuel into the exhaust manifold on the others giving you lots of very hot gas to spin up the turbo (and the cyclic idle is there to help cool this down and keep the revs sane with the throttle open ~20% when "fully closed").
its not great for your turbo or cat (which will not last long before its insides are smashed to pieces/melted) as you pop and bang when the engine revs drop between gear changes/exiting corners keeping the turbo spinning nice and quick. this keeps the turbo ready to come on boost as soon as you get on the loud pedal so you get less of the wait as a turbo spools back up, it can also be used off the line to launch at full boost but you need a lot of grip to keep from just doing a burnout instead.
you need to keep in mind that this all requires someone to set it up in the ECU/TB, it is more than just a case of turning it on and it working out of the box.