After attempting the new bosses once each (so please note I am by no means an expert XD) I figured I’d share my experiences and speculation because everyone appears to be lost and running around like a chicken with its head cut off.
Marionette
There are 5 different paths that lead to the marionette. Everyone needs to split up equally along those paths and kill the mobs before they reach the portal. This will prevent the death star charge bar from going up. After a while, you will be able to go through the portal and fight the marionette. Kill the mob on the platform you are on and then kill the controller on the other side of the platform. This will shoot a laser at the marionette dealing damage.
Each path will get their turn to go (south to north) (this is why it takes so long if you are on the northernmost path) and they go inside the open portal, spike down the champion on the platform, destroy all the controllers, then they get popped back out into the tower defense tunnel again.
Some things to help are the barriers you can build to make the champions path to the gate take longer, the arrow cart that spawns by the gate, and the 2 golems. If all goes well, once all 5 paths go and sever a chain you win! Your reward at the end is based off of how many chains were severed.
Giant wurm
Once again, there are 3 paths to split everyone between (One for each head). Do the 3 escort missions, and then the wurm will spawn.
Crimson wurm (Middle):
To kill the worm you need to run through the clouds of phytotoxins or something like that and it will give you a teardrop shaped colored marker (red yellow or blue) above your head. On the mini map, there will be a spot to run to for each color toxin. Run to it and continue doing this. Eat nutrients along the way to help prevent damage from his drool, and have a group of people killing the eggs and mobs that constantly spawn.
Once all 3 colors are full (theres no progress bar so its a little chaotic), the devices will shoot the wurm, which will fall to the ground making it vulnerable to attack. Spike it down as much as you can. It will get back up after a fairly short amount of time, and you have to start the process over again. In the 15 min window, my group only managed to get the wurm down twice and spike down less that 1/4 of its health…
Cobalt Wurm (Northwest): Fight off the adds while you ferry bombs to the base of the Wurm head (at a red arrow); after 20 (unconfirmed) bombs are placed in a short period of time, the slime coating of the wurm will be breached, allowing you to attack it. Repeat until defeated
Amber Wurm: Same as others…Kill eggs before they hatch to prevent being overrun by champs. Kill the wandering Risen Plauge carrier, once he explodes youll have a buff on you. 20 people with this buff need to run in front of the wurms head (there will be an arrow), the worm will eat you, them being vulnerable because of the poison. rinse and repeat
Please reply with your experiences so I can update this with them so we can figure out the best strategy. This is going to be a work in progress because of how new the events are, so share your experiences and maybe things will run a bit smoother =P.
(edited by Toxic Massacre.9870)