This trick lets you level up cards too easy, plus you can plow through levels and have basicly all your cards when you get to the bosses.activate the Green Guardian combo (elf, elf lord, dark elf) and have the octobush on the field at the same time. The elves constantly heal you and the octobush, while the octobush constantly heal the elves. With this combination, you can beat most of the levels with out even using other cards. They just follow you killing everything that gets near while you can sit there and worry about nothing cause everyone is always getting healed.To level up cards very easy, goto the Fossil Boneyard towards the end where you are surrounded by baby dragon caves. Just do the trick there and leave the game on for however you like and the elves will just slaughter everything that pops out the caves.