Here's this Infested ruins nightmare survival afk Build that I've built myself and is pretty much foolproof and the the afk summoners never die as I've tweeked it enough that I don't lose to any rare chances of ogres not getting aggroed by lightnings and hitting a crystal, harbingers killing my afk summoners as they try to feed off the mobs, or other random things that I've ocasionally lost to with other builds I've used for this map that focus on a more centralized defense for 1 crystal and only traps and aura's covering the rest: I'll be discussing in detail the general layout of the build and the reasons behind some of my choices I've made in this build's particular layout down below.

note: Green arrows indicate seed bombers facing directions, yellow arrows the strikers facing directions, the different colored lines indicate the corosponding minion wall formation, marker 5 is where you should place your afk summoners with their dijinn and imp pets, the dijinn can shoot through walls so they should be completely fine at those locations.

Layout

Small Update: I've removed the reflect beams since the forest golem at marker 1 will make even apprentice towers noticiably tanky enough so that you don't need to worry about them falling to wear and tear from enemy projectiles anyways, all to make room for 1 more gas trap to cover the eastern crystal as I've noticed ths ocasional goblin or archer will head that way rarily, I recommend decreasing the trigger radius of it so it fits the pathway so it only activates when a mob heads towards the crystal.

Towers: I've split the defense into 3 choke points noted by the 1 2 and 3 markers, marker 1 is where the main stack of towers are is located directly behind the western crystal, 1 seed bomber is seperate from the stack and placed at the edge of the platform on one of the pillars still covered by the stacks 4du buf fbeam, and faced north to cover, the western crystals north choke point, the second one is inside the hermit/apprentice tower stack and is faced west to cover the main western chokepoint, there's 1 striker facing west and 1 forest golem to help take down any ogres and wasps, the other 2 strikers are faced south east to cover the 3rd markers chokepoint for the central crystal to make sure the two lanes of wasp that path through their are kept in check, marker 2 is only covered by a snare aura, gas trap, inferno trap, darkness trap since only trash mobs pass through there make sure the inferno trap stretches out further towards the mobs 2 paths than the gas trap does so the mobs don't start clumping up, marker 3 and 4 is where the second stack of hermit towers is placed 1 bomber is facing east, the other is facing south, the golem is there to help with the ogres and keep the harbingers from killing these towers with their ranged attack, marker 4 is where I place the nature pylon that has just enough range to cover the two archer walls and where I move the mage minion to heal all of them without getting bashed by ogres.

My reasoning's for this particular setup:

First and formost, I have that snare at marker 2 and so that warriors don't reach my afk summoner to the south of the middle crystal, the mushroom in the hermit tower stack at marker 3 and the 2 strikers pointing south east at marker 1 will finish off anything that surives

The Mine trap over the archer wall to the west of the western crystal is to make sure no kobolts slip through my archer wall there and kill the run, as ocasionally the ogres will make holes in the wall as they nudge the archers.

The beam wall on the stairs to the south of the west crystal to to prevent any ogres that fall to the lower level (very rarily happens, but it can happen) from hitting the crystal as they head through marker 2 and up towards the western crystal before dying to the forest golem there

I have orks blocking the north choke point to the western krystal due to the mobs tending to hit the minion wall there pretty hard if you don't immediately upgrade the buff beam for them there

I have my second tower stack at marker 3 instead of closer towards the middle crystal cause my previous builds that also used seed bombers a lot had he mobs clumping up a lot behind the statue that was blocking line of sight to the foot of the stairs leading up and also to make sure no mobs aggroed towards the east crystal, so far I've yet to have a mob head towards that one with this build despite only 1 seed bomber and the snare and streangth drain being the only things that cover the path to it (thanks to that golem there probably)

upkeep: the only things that kinda need repairing that aren't covered by afk summoners is marker 2's traps and marker 3's pylon, if you have decent health for your traps each charge lasts so long that you can go a few waves without repairing them if you want but you'll be heading near them for the chests after every wave so might as well flash heal them while your at it, and the pylon unlike the buff beam takes damage whenever the towers around it recive damage in exchange for not going down when something dies in its radius, it usually takes about 30% after a wave so you'll want to repair it inbetween waves as you head for the chests past it. I suppose you could skimp out on the beam wall and replace the pylon with 2 buff beams to remove that little bit of upkeep though I haven't found a way to cover marker 2's traps with an afk summoner as ocasionally a harbinger will fall down to the lower level and head through marker 2 and up towards the western crystal and sit around stairs their. and directly placing an afk summoner around marker 3 tends to get them killed by harbingers ocasionally.