The other approach for a hammer in a footslogging list Betray using your wyche template would be this
14 Wyches, Haywire, Hexatrix, Venom Blade, PGL
- 568 -
2x 15 Wyches, Haywire, Hexatrix, Venom Blade, PGL
2x 15 Guardian Defenders, Scatterlaser
- 720 -
2x Talos, TL Liquifier, TL Splinter Cannon
- 210 -
The list is replete with both AT and AI. There is no AA at all really. However you are flooding the table with five scoring units and two MCs. If you spread out those seventy-eight models will take up a good amount of space. This makes it difficult for your opponent's flyers to maneuver and also prioritizing is not as simplistic as it seems. You want to kill the Taloi in the middle of the Wyches as they advance. You want to kill Jain Zar and Lilith but Zar has EW and can tank wounds like a champion and you don't mind losing a few ablative wyches.
Now Zar's unit is both bait nad hammer. You don't mind if it is targeted a bit as it surely will be. The threat comes from everywhere. The guardians have battle focus and firepower. The wyches have haywire and assault capabilities too and the MCs are just plain dangerous to everything. PGLs are both assault and defensive grenades - this is important to remember as well. This leaves your opponent with the only option to fire at your army as they will not want to be engaged in combat.
By turn two or three the list will begin engaging the enemy. There is no escape. Your opponent must hope he has done enough damage by then to mitigate the effects of combined assaults. So when advancing you use every trick that you have at your disposal. LoS blocking terrain, cover, fleet, spreading out and battle focus - you will lose a few models probably. But you should have more than enough left to deal some hefty damage on arrival.
When you go up in points you can add warp spiders, war walkers, small beastpack or crimson hunter to make the task even harder and assault both head on, from reserves (DS otr flyer) and from the sides (outflanking walkers). The options are all there.
Paper is overpowered. Scissors is fine.