Arent the new Fire and Water Dragons.... OP ?
If this isn't OP....
Fire - Gives up to 24% AP and AD, +50% if they have Mark of the Elder Dragon. Water - Up to 10% of your max HP and mana every 6 seconds, 15% if they have Mark of the Elder Dragon.
If this isn't irrelevant....
Earth - This unit deals 10%/20%/30% additional damage as True Damage to Epic Monsters and Towers, +50% if you have Mark of the Elder Dragon Air - >This unit has 15/30/45 (based on stacks) additional Out of Combat Movement Speed, +50% if they have Mark of the Elder Dragon.