I would like to present you Altar of Despair Midrange Assassin deck:
As you can see on the curve there are mostly 2-drops(14), six 3-drops and nine 4-drops that is the mark of midrange deck.
The concept of this deck is to to support a good tempo on the board from the early game, control it and triggering Last Gasp effects of the creatures by different ways.
The win condition of this deck from aggressive ones is to control the board before playing
This deck will be pretty good against midrange decks especially if you control the board and play tempo game. It will be hard for your opponent to remove your creatures with Last Gasp like
This deck have a bad winrate against control decks especially if that decks have cards that can destroy