4e push/pull/slide

[cavanaht]

First off, rather new to 4e, so my knowledge is a bit low.

I created a Deva Invoker who is going to specialize in pushing/pulling/sliding enemies and allies alike around the battlefield.

I have taken the Covenant of Malediction (push 1 creature 1 square when I use a daily/encounter power)
I took Superior Implement Training (Quickbeam Staff, adds 1 to any push/pull/slide effect)
I plan on making/buying a Staff of Forceful Rebuking (adds 1 to any push/pull effect)

What else is there for me to increase the push/pull/slide effects?

Is there a way to convert push/pulls into slides?
I'm looking for any legal source.
Thanks!

Here is something I used on the past session (we are level 2 now) and I was wondering if this was legal:
Use Maledictor's Doom (minor), then use Astral Terror (standard).
Because both are encounter powers, would I be able to move a push a creature 4 squares because of the Covenant Manifestation?

[Kurald Galain]

Multiclass to wizard, then take Orb Expertise (adds +1 to forced movement) and Glowering Wrath (adds +2 more), then wield an Orb of Irresistible Force (1/enc free push).

[Pinnacle]

Make it a petrified orb of irresistible force.

A petrified orb is a superior implement that grants +1 to forced movement and +2/3/4 (depending on tier) to force damage.
Of course, you may prefer to spend your Superior Implement Training on an accurate orb (+1 to hit) to improve your chances of push-/pull-/sliding in the first place, especially if you don't deal force damage.

[cavanaht]

Wouldn't the Quickbeam Staff of Forceful Rebuking add 2 to any push/pull/slide effect already?

I don't really understand what multiclassing to wizard would really get me.

If I did multiclass to wizard, I would be using the orb of irresistible force and push things 2 squares. Or I can stick with what I have and do the same thing.

[Kurald Galain]

I don't really understand what multiclassing to wizard would really get me.
Glowering Wrath and Thunderwave, one per encounter each.