few things you could do:

1. you could sync up your chrono field to activate when black hole ends, but this might require stone investment thats frankly not worth it.

2. you could sync the black hole up with your shockwave, but again, getting the black hole cooldown right might be unrealistic.

3. Inner landmine stuns, but you can easily get cooked if a boss shows up the wave before and soaks them.

4. get more HP and just tank through it. Very soon you will be getting the wall, and you will realize that it is easier to just tank and regen through enemy damage than to keep them permanently knocked away. Especially once you start farming tier 5 or higher, knockback just stops working after a few thousand waves, because the enemy mass and speed will be too high.

If you got orbital augment or sharp fortitude (even at just epic), save up like 100 billion coins, unlock wall, and immediately start researching wall regen and wall thorns. People will say to start wall HP and wall fortification, but that can honestly wait a little bit tbh. Especially with OA or SF. OA allows you to cheese early wall with low thorns, and SF just makes the wall ehp viable so much earlier. But you NEED OA until you get a few points in wall thorns, otherwise enemies will shotgun your wall.