Most of the protection spells Ive used were cards like Not Dead After All, Malakir Rebirth, and Fake Your Own Death
As we have seen with DRC, Delirium is not very difficult to get, especially in a format with Fetchlands and Mishras Bauble
The card is very strong, especially in self-sacrifice decks (also known as Aristocrat decks), as you get the advantage of your creatures dying while forcing your opponents to exile creatures
Your opponent trying to challenge Hydra will also have to worry about having their other characters damaged in the process
That first ability resembles the shenanigans you can get up to with Dargo, the Shipwrecker, so in the right deck, you can cast it for two mana, attack for seven (that can only be blocked by legendary creatures), and then sacrifice it to destroy an annoying artifact or creature