Maybe this card is amazing at your local game store but not quite as good at your kitchen table, or vice versa
Mega Froslass is not good simply because of the instant damage itself, but because it forces you to limit your hand throughout the entire game, as any Snorunt on the bench could evolve and oneshot you with one energy attachment, and this way it limits counterplay to other attackers that synergise with the Snorunt line
They ALWAYS have the perfect card for a situation, but that card only works in that ONE EXACT SITUATION and as a result, new players (like myself once) would always load up on cards with undeniably good effects, but so situational, so hard to setup or summon, that they were functionally useless in a real duel
If you're the monarch, until end of turn, you may cast a spell from among cards exiled with this enchantment without paying its mana cost