If this spell was cast from a graveyard, you may play cards this way without paying their mana costs
Hayes In short, hexproof just means that a card can't be targeted by any spell or ability controlled by an opponent
Theres a few Azorius snow cards that tap your opponents creatures or prevent them from untapping, including Icebreaker Kraken, and you can supplement them with other tappers from WOE and other cards with icy or snow card art
For four mana, I can deal X damage to target creature or planeswalker, where X is the greatest power among creatures I control and if it would die this turn, I can exile it
Notably, those decks don't even have to be dragon-based to get serious value from Two-Headed Hellkite, since any deck would benefit from having a huge flying beater that draws cards generously