Tactics for playing against Sylvan.

Why would I summon the "Song of Peace" when it's more of a basic spell? If we're talking about summoning phoenixes or dragons, you'll probably end up with more of those in your army. As for the protective spells, the main thing is to cast them in time. By the way, in what order should they be cast?
P.S. And what if the hero is wearing a "Guardian Robe"?

Added 2 minutes later
It's better to use "Song of Peace" on unicorns if you have them, otherwise those horned creatures will blind half your army, and you won't have time to remove the effect.