Marrow-Gnawer sac-loop: tap Marrow-Gnawer, sacrifice one Rat, make a token for every Rat you control then swing with fear for a one-sided alpha strike
Tying Clue generation to a passive action like playing lands can immensely help your early game, both in giving you a creature that gets stronger over time thanks to Tireless Trackers second ability, and one that helps you dig for more lands by drawing even more cards
Such is the case with Darkness, a low-cost instant which prevents all combat damage that would be dealt that turn
Ive seen games where Archangel landed on a modest board, and two turns later, everything was massive
Put these ideas together, and I have the impression that the set is designed to allow players to have time to find their favorite legendary characters and use their abilities
Its also part of a number of infinite mana combos, my favorite of which is the more aspirational than realistic Old Gnawbone and Hellkite Charger