The Way Out
This took me five tries, but the last four were all trying to get all three were not for strategy. The last three were because it took me three tries to make it so that each time an abomination+ popped, I then popped all three Monstrosity+ at the same time (or near enough so that with knockback and the range on crystal I could hit all 18 worm+ with a single crystal).
Azra: Books of Plagues and Blood. Max out lightning, crystal, and dragon fire. I put 6 points in heal, 5 points in knockback, and the rest in Frenzy. Markos and Ketta don't do huge amounts of damage, so Frenzy is pretty mediocre.
Ketta: Warlords Triumph+, Master of Archers+, then max all damage dealers except Spread Shot, including critical and poison. One point in Piercing Shot and the rest in range. (or switch those... either is good).
Markos: Evni+ or Edge of Order+, Strength of Wolocan+. Max out Armor Break (probably un-necessary), Armor Training, Sword Training, Hard Knock, and Stun Stab. Then assign points into attacks as you please.
Place Ketta in the middle so that she can hit near Azra but also as much of the rest of the path as possible. Place Markos on the bottom near the entrance (the corner works). When the third wave spawns, move Markos to the top. Then, when the abomination spawns, move him to the corner nearest the bottom entrance and have him follow the abomination and monstrosities around until they are dead. He should be set to attack "strongest" to make it easier to kill all three monstrosities at once. It costs 745-558=187 psi to move Markos, so make sure he is going to do enough damage on each move (~50,000) to make it better than just casting lots of lightning.
As far as spells are concerned, you will need crystals for the worms that pop out of monstrosities, and it's good to have a knockback to push the worms back while killing the 2nd/3rd monstrosities. Other than that, cast spells to do the most damage. I use crystals in corner spots to hit large groups of enemies, and I like to dragon fire near when the worm waves finish. The basic spell-casting advice is to cast as few lightnings as you can get away with. Not only do lightnings cost psi, but they lower the psi reward of the target! If you use lightning willy-nilly, you will run out of psi. For the most part, you don't need to cast lightning on anything more than 3 squares away from Azra (but inside that zone, cast like mad!).
The core difficulty of TWOE is the abomination/monstrosity/work issue. As I mentioned before, if you can get all three monstrosities to die at nearly the same time, you can use a crystal to mostly kill all 18 worms, and then easily pick the rest off with lightning or dragon fire or even let Markos and Ketta kill a few. If you get two monstrosities to die at the same time, that's fine. If you have both dragon fire and crystal ready, you can use crystal on the 12 worms, and then dragon fire on the other six. It is also possible to kill six worms with lightning before they travel more than 10ish squares. Obviously, the final two abominations are insanely difficult because you need to put enough time between their deaths for crystal to refresh. This means heavily focusing on the top one and killing it as quickly as possible before switching to the bottom. Run the game slow and cast lightning to help kill the top abomination and his monstrosities quickly. Just also remember to pay attention to Azra... don't let her get hit! Then use Markos to stun the bottom abomination so it doesn't move very far, and try to arrange for the monstrosities to die exactly as crystal becomes available again. It's not easy, but far from impossible.