Too glossy and you get glare
Delve is a fantastically strong mechanic in any format with cheap spells and fetch lands, and getting the best two out of seven cards with no drawback is a huge advantage
However, it was also in 1996 that Alaskan Magic player Adam Staley created a similar format, which he dubbed Elder Dragon Highlander. The Elder Dragon part referred to the legendary dragons from Legends , like Nicol Bolas
You lose life equal to that spell's mana value
For now though, it seems like all four are worth checking out
If your untap step is somehow skipped as your next turn begins, your phased-out permanents won't phase in until the next untap step you actually have, but you'll no longer have protection from everything and your life total can change again