Tournament rule 703.7

Insufficient Randomization [Warning]: A player did not sufficiently randomize their deck when required to.

• 703.7.a If a player believes an opponent has not sufficiently randomized their Main Deck or Rune Deck before presenting them…
• 703.7.b Pile shuffling is not a sufficient randomization method and should only be used as a counting method.
• 703.7.c Remedies:

Official Tournament Rules