"Although it looks like a seemingly tranquil forest, this place shelters terrible creatures that seem to have come out of our worst nightmares. These mutant soldiers known as Behemoths were created by the ancient humans to kill the infected ones, however, they eventually succumbed to the pandemic and are now part of the enemy. The Behemoths seem to concentrate on the Forbidden Forest, so your mission will be to annihilate them because there will be no peace for the Empire while these creatures walk the earth."
This is the first map which introduces Infected Behemoths. The amount of Mutants present on the map from the start depends on mission difficulty. All types of special infected are present as well, but only above chokepoint in the center of the map.
The last wave on day 49 consists entirely of mutants.
Swarms can only come from south, east and southwest. Northwestern and northern passages are actually impassable.
There are big gold veins in the middle of the map and on northwest.
There is a mutant just northeast of the base. It's over mountain, but it can still be pulled by noise; if it does, it will arrive from north.
First things first -- DO NOT underestimate the Infected Behemoth. Infected Behemoths are extremely fast, extremely tough, and can multihit shockingly hard and at surprisingly long distances. They can, for example, hit towers like Ballista or Executors on the other side of full-width walls if the towers are right next to the wall. Infected Giants hit harder and have much more individual health, but are also deaf. Behemoths are not -- they are even more sensitive to noise than Harpies, and you'll face quite a few of them at a time on this map.
If you've been pumping your Soldiers with the tech tree to this point, a good troop of 30-odd soldiers can handle individual Behemoths, which will serve for cleaning out the map provided you take care not to pull the whole collection at once. If your Soldiers are not pumped, then Snipers and Titans are your best bet -- Titans can actually stand up to a Behemoth one-on-one for a brief stretch, far better than the other Engineering units, though Snipers are much more effective for actually killing them. While this map has a lot of clearing out to manage, its true challenge is the final wave.
First things first, though. Use your Rangers as much as possible for your initial clearing-out and hold off on an initial Soldier push -- too much noise will alert the lone Behemoth northeast of the base, and if he comes around early then you have almost no hope of stopping him*. Send your soldiers west of the CC to hold the line at the stone deposit and the south shore of the lake, which south-entering leakers will favor. Your Rangers should first clear out the far side of the tracks southeast of the CC, just to make sure, and then sweep the area due north of it, circling northwest. It is also recommend to kill the first behemoth before the first swarm. Around 20 Soldiers, 2-3 Great Ballistas, along with some towers and walls, are fairly enough to deal with it and the horde it may attract.
*Note: Even in apocalypse mode (it was tried and worked on first time) it is possible to stop that behemoth, but it's a complex thing to do. If you spent your tech points on many mercenaries, and you have 2 soldiers, sniper, and prefabricated materials (free ballista at the start), and you prepare well for that mutant with 2 or 3 separated wood towers, you can can force the mutant to hit one tower while all the units are hitting him hard. If you do it this way, you are capable of actually finishing him off. In addition, Artillery transport can help you too, and if you have no wood tower, the best is to make the mutant attack your Command Center since it's the only bulky thing at start and may survive even a behemoth till all the soldier finishes it off. Note however no matter how you manage to kill this unit, even if you do so you will still have to face lots of zombies who may attack you, because of the sound you've made. But they can still be repelled if you guide your units well. You can also use the train to hit the behemoth or many other zombies to cause them massive damage, and make it even easier to deal with them.
When you hit a derrick just below a gold deposit, that's your chokepoint to the north -- wall that off and then secure the immediate area. Your Rangers should staff this chokepoint, and the rest of the clearing-out south of it can be handled by Soldiers and/or Snipers. Be careful proceeding north of the long lake -- the two Taverns of Evil in the woods up there can rapidly overwhelm you if you're not prepared for them. It's very probable that the first wave will show up before you can secure both the south and west map entrances, and as such, you may have to set up a temporary line to intercept that. Once that's handled, however, complete your securing of the southern half and assemble your chosen deathsquad.
Have your deathsquad then start clearing out the north. Follow the curve of the gold deposit, first moving around to the final map entrance in the east, then up into the big forested area, and then finally around the river up to the final stronghold. Be cautious -- it's very easy for sound to trigger enemies from the far bank of the river, including the various Behemoths. When you pull a Behemoth, make SURE you focus fire it when it appears. Once you've started securing the north build up on the gold deposit, make multiple barracks, and start cranking out troops. You will need as many Soldiers and Snipers as you can manage -- 300 Soldiers or 120 Snipers may well be necessary for the final wave.
The final wave, you see, consists exclusively of Behemoths (around 1-2 dozens per entrance). Any defenses you have up for regular swarms will get chopped through like rotten plywood by that kind of assault. After around Day 34, or whenever you secure it in the first place for the east entrance, rework your defenses to make sure you have multiple-layered defenses on every entrance. At least two max-thickness walls, preferably more, and as many towers and heavy turrets as you can cram in. Anyone who you can't fit in the towers should stand behind them. Make sure if at all possible that high-Worker buildings like your Wonders or research plants are out of the direct path between the entrances and your Command Center, especially the south entrance as it has the shortest travel distance.
Even with these defenses, the Behemoths may breach your lines. If this happens, make sure to preserve your military, fall back, and clear out any spawned chaff first. Chaff will usually try to beeline for your CC, whereas the mutants have a high change to be distracted by other buildings, especially parts of your defensive lines that aren't directly between them and the CC. Keep your guns firing for as long as possible and you can show them just who is the true superpower here.
On this map the closest behemoth is a great threat to your colony. However, it is killable early if you spend everything starting advance (on technology tree) you can kill the behemoth on day 0. The fastest recorded kill on behemoth (on 800% difficulty) is day 0, 22 hours so far. (This game was lost however)