Okay, guys. Listen. I get that this card is extremely scary on paper, and yes, there COULD be that one duel where it just locks you out. But I consider it so damn niche and situational, that I can overlook the power such an effect holds. The fact it uses the hand for one is already what makes me think it's a good enough restriction in its own right. Okay, sure. Maybe someone like Leander can use it, lets say, because his hand is pretty stocked by having a good amount of deck summons. There's also the consideration he has to draw the card, get it on the field without it blowing up (since it has no built-in protection) and then making sure to protect it from all card effects JUST to be able to negate some internal summons, which wouldn't help him against some other players.
I can't think of anyone else that runs a strict LIGHT deck off the top of my head, but lets switch focus to Vincent because Chaos. Sure, he can keep his graveyard stocked well enough to bring it out. But from what I've seen, honestly, he doesn't have much of a hand when it gets to that stage, or at least no strict LIGHTs in there. With him, the most prominent thing is the ATK gain (which, to be fair, after thinking about it I shouldn't have made universal for either card to fit with theming). He can maybe negate a single summon, but anybody else with even a little swarm potential could probably get out of that unphazed and pull a second monster out with ease. Then there's the factor that some, though not all, characters rely on effect special summons which don't really get affected by Eos at all.
Bottomline, I agree the card is powerful. Okay, MAYBE it needs a nerf and/or limit. The thing is, considering not everyone can use it AND the situation has to be just right in order for it to work, that it gets a pass for now. If it PROVES to be a menace I'll nerf and/or restrict the numbers of copies you have. But I can't see it being much of a menace, not now. Not with the current state of things.
EDIT: Brad and Camryn have straight LIGHTs too I think? Even with them I don't see it being an issue...
...Hell, Brad might be the most scary with it. Worms aren't the fastest things in the world.