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
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
Additionally, Thought Vessel also has a higher risk of being removed with an Artifact removal than Reliquary Tower, since not removing lands is an unspoken rule in Magic: The Gathering
Such is the case with Darkness, a low-cost instant which prevents all combat damage that would be dealt that turn
With its next appearance in the Shadows over Innistrad block in 2016, the mechanic saw a big change in how it worked
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