This build is a variation of Quiche078's build so most of the credit goes to them for the main structure of the build. The main difference is that the Apprentices towers have been replaced with Guardians towers. The main purpose of this build is to show how i made it work for me and help others who might be having similar issues. I was having trouble with my characters dying to harbringers etc... so this is what i did:

My builders have around 7k in their main stats.

Wave 22: Build everything. Make sure to hit both aura stacks in the middle with your buff beam, this can be difficult depending on your stats and how you place it, so use a temp beam if you need. You should see a little mushroom patch where Hint 1 is where you start your 4DU buff beam and then aim towards the centre of the island. You should be able to stack everything in one spot at the end of the buff beam other than the mushroom if you build the towers at Hint 1 left to right (Tower stacking required). 

I usually have 4 characters in from the start because ill be doing back to back runs so theres not much point taking them out for 1 round. You will want an upgrader and your tower booster for the first wave. You should be able to upgrade everything in a single wave but its not a problem if it takes more. Put your tower booster in the little tree right next to the tower stack and aim at Hint 3 (Make sure the monk is still in the golems range).

Wave 23+: Swap your characters so that you have 3 Summoners and your tower booster. You want to get your Summoners on the statue that is next your tower stack, the big tree behind it can help you with that. Glide up it with the summoners hover/fly ability and then drop down onto the statue, you should easily be able to fit all 3 Summoners on the top of it. From my experience they are safe from taking damage here whilst also being able to reach the towers with their pet guardians. As for those pet guardians I use: 3 huntress, 2 monk, 1 apprentice and 1 squire, but there may be a better combination.

You should be able to chill out and start a tower boost at the start of the round and basically afk it, might need to do a refresh of your tower boost on the last few waves as they can get quite long. The towers and aruas at the far west should be able to last without needing healing for the whole run but you can easily repair them with your Summoner if you need to. I don't tend to grab chests as it is rather slow during build or dangerous if you do it during combat.

This is what the build should look like when you are done, also showing where your characters should be:

Aim here to glide up the tree onto the statue with summoners: