Can Riot-branded sleeves with transparent/non-opaque backs be used for main decks in high-level OPL tournaments?

Ruling: No, Riot sleeves with holographic patterns or reflective/transparent backs are not allowed for high OPL play as they violate the opaque sleeve requirement.

Nuances:

• The sleeves were observed at the Houston official event, but this may have been a special exception or early ruleset specific to that event
• Marked cards in the main deck provide significantly more valuable information than in side decks (like Rune decks)
• Individual stores may be more lenient, but the official rules require opaque sleeves
• Just because something occurred at a streamed event doesn't establish it as a universal rule