Instructions
Build a creature capable of killing an Epic monster. Add parts to your creature to give it flight, herbivorous diet, level-5 spitting weaponry and to increase its top speed and jumping abilities.
Get the Epic creature's attention, and lure it to another Epic monster. The two will battle to the death at first sight, and the winner will be at half health.
Attack the Epic creature with your creature's high-level spitting attack from a long distance. Most Epic creatures attack by stomping, kicking or biting, so the more distance between your creature and the Epic beast, the better chance your "Spore" creation won't die. Flying, jumping and the speed boost you gave the creature will keep it alive while outrunning the angry Epic creature.
Keep the Epic creature in sight at all times. If you go too far from the Epic monster trying to get an even safer distance for spitting, the game may give the colossus full health. Your creature will get hungry at some point during the battle because Epic creatures take so long to kill. Eat fruit and plant material in the wild to keep your hunger at bay, and continue to spit at the Epic monster while luring it to your creature's nesting area.
Get the Epic to your species' nest, and continue spitting at it. If the Epic kills your creature in this area, you will reappear on the nest ready to attack once again. Quickly spit at the Epic to get its attention before it walks away. Don't worry if your creature gets slaughtered repeatedly, because you can snipe one or two attacks on the Epic between deaths to slowly kill the leviathan.