For Survival Mode, have a conjurer with Battle Golem and have the golem health go up as high as it can, it might take a while but slow and steady wins the race
I have gotten all upgrades and all achievements! This is my two dream teams, (i hope this helps) Mighty Guardian, Phantom Ghost, Were-Tiger, Sylph, Valkyrie, and Orang Utan. This is my other one, Phantom Ghost, Might Guardian, Great Diablos, Sky Dragon, Lord Of Fire, and Celestial Angel. Both are very good at Epic battles, but the first one is better at epic than the first.
Ok a guide is in order! 1st Restrain him. 2nd Give him Mutation X until he stops changing. 3rd Put down raw meat. 4th (This will take a long time) Wait until his mutagen level (in exp) is at 0. 5th 'Unrestian' him. Because there is food he will eat and because there is no mutagen level he won't get hurt. Voila Spider Rat. Bonus Step! Between steps 1 and 4 you can give him metal body parts, he will still live. I hope this helped you!
 "Rebuild"){kind=icon}
 "Rotatix"){kind=icon}
 "Epic Battle Fantasy"){kind=icon}
 "Monsters' Den: Book of Dread"){kind=icon}
 "Epic War 3"){kind=icon}
 "Epic War 4"){kind=icon}
 "mutate the labrat"){kind=icon}
 "Bloons Tower Defense 4"){kind=icon}
 "Toss the Turtle"){kind=icon}