Suitably enough for the Dimir, playing with Duskmantle Seer comes with the risk of eventually killing yourself from gaining too many cards — but could kill your opponent as well. Because of the Seer’s particular wording, his ability can sometimes result in a draw.
The wording of Duskmantle Seer’s ability is very specific: it only triggers on your upkeep, and both players reveal cards and lose life simultaneously. If both players end up going to 0 or less life due to his ability, they will lose the game simultaneously before anyone can do anything else, resulting in a draw. You won’t have any chance to gain life, cast spells, activate abilities, or even use triggered abilities before the game ends in a draw.
If a game in a tournament ends in a draw, shuffle up and start playing another game! The player who made the choice whether to play first or second in the drawn game gets to make that choice again for the next game. You keep playing your match until one player gets two game wins (or time is called).
Today’s Rules Tip written by Paul Baranay