Reliquary Tower A staple contender, but I think it only locks slots in blue and black decks or other decks that dedicate a lot of time to building their hand
There are artifact types, enchantment types, creature types, land types, planeswalker types, battle types, and spell types that can be on either instants or sorceries
Of course, you'll want to replay Sephiroth to do it all again for a second, third, fourth, fifth, or sixth emblem and make every death hurt as much as possible
Due to the frequency of having a spare single mana combined with the fact that spending 2 to draw a card at instant speed when you start to run out of gas is fairly painless this card feels a whole lot cheaper to use than it is
For example, Final Act is a hateful little showstopper which is particularly useful against opponents with Energy decks
Until your opponent is corrupted, that is