Yes, apparently any of those spells that creates a ring of 'flames' around the battle increases ALL spells, not just yours but the monsters too. They all look the same on the card, with exception of the color, depending upon the school of magic, and each one does something different. For Balance, it increases pip chance, for life, it increases life heals, for storm it increases damage just as it does for myth. I think for fire it probably also increases damage, though I'm really not sure for ice or death (if there is one for death even).
With my life wizard, I will use it except when fighting life monsters (or monsters that I find use life heals even if they aren't life), because their heals already drag the fight out too long as it is. I stopped using it on my balance, because even though it upped her pip chance, I found the monsters just incessantly cast their huge attacks nonstop, causing massive damage, while I still have to wait for pips to build up.
Mkay, So I'm a level 29 Myth Wizard, and I keep wanting to use Time Of Legend, But The amount of myth foes i'm fighting makes it seem risky, I mean do their attacks get boosted aswell?
Yes, if you are facing Myth opponents, their attacks will boost too. Best to use this spell when you aren't fighting Myth opponents. Time of Legend is a really great spell for Myth, especially in the frog spamming strategy (buff once for several attack payoffs later).