Allmeggdan isn't all powerful. Most creatures with 2 or more elements (thus creatures who can deal more damage with Allmeggdan) usually only have about 40 or less energy. Focus on taking those creatures down first with strong mugic cards or though simple battling. Try equiping a creature with a skeletal steed or put a creature with swift and range in your line up.
By wiping out the creatures that can deal alot of damage with an allmeggdan, than you significantly reduce the chances of being koed by it.
Also you can always try throwing out a song of future sight and hopefully snag that allmeggdan to the bottom of your opponents deck.
Strategy is buying a bottle of fine wine when you take a lady out for dinner. Tactics is getting her to drink it.
Chaotic Insider: Tune in every week for the newest strategies and tactics for the Chaotic TCG