Freya is a better healer, but Shalana is better support all heroes near here spring get +5%/10%/16% attack and Def buff if your using Minamoto as well it stacks with his hero of the army ability which gives 5%/8%/12% attack and 8%/12%/15% Def buff.
If you’re a water player then the best setup is Roland, Minamoto, Medusa, Shalana, and Pandora (dark hero, but she gives a 7%/9%/12% attack buff) these stacking buffs the heroes give to one another make them a formidable team as far as raw power. also on Roland, you use him over Poseidon because he is a far better tank as far as def & HP. Poseidon dose far more damage than Roland however if the point of the hero is to tank then its best to go with a tank of tanks. Also, Roland can revive other dead heroes as well as heal others and himself.
But the ultimate healer you want is Frigg her rage increasing ability is just OP.