Seems very, very fun indeed. I'm curious as to how strong this is in practice.
Thats a good question... I actually have no idea really.
It gets the most kick out the ability if used on a winning coin toss with novas and / or towers... Of course, it will be near impossible to also have nightfall or eclipse out by then, so it would only be doing 1 damage at that point.
The other use is a counter to having players spam the same card or ability multiple times in one turn. It would be deadly to decks that are built around a single ability, like RoL hope, Devourer Denial, vampires, etc.
Against other decks, its basically just a nice low cost rusher.
Getting 2 to 3 damage per turn out of 1

when nightfall or eclipse is out isn't too bad. Its actually a bit stronger than 1

creatures of other elements... Nothing a titanium or diamond shield wouldn't thwart, but certainly very good for the cost.