Elements with their specialities
Water - magic ( great for armored matches as magic ignores armor )
Fire - melee (Great for SNEAK battle , unless you have Mylor use him )
Earth - health (Earth has a lot of great tanks ! you can use them for back to basics ( when monsters lose all abilities) + Earthquake/poison battle )
Life - Shield/health (Great choice for poison battle ! )
Death - Debuffs ( for low mana matches Death is often good , along with its debuff effects )
Dragon - Flying (dragon cards are all great ! i love them + you can use one more splinter along with it )