This is a common tactic employed by Dragon players in the face of defeat (Necromancy even let them do at instant speed so they could respond to lethal damage by forcing a draw) and so it was not too uncommon to see matches with Dragon decks go to 4, 5 or more rounds
C Slate Street Ruffian An interesting, readily available cipher target that forces the opponent to either get hit and suffer the encoded spell, or block and (hopefully) trade and lose a card

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While its four-damage-for-two-mana mode is almost always the best choice, this cards other two modes are nothing to sneeze at temporary indestructibility for all of your permanents is pretty sweet, as is granting double strike out of nowhere to sometimes end games on the spot