Sentinel

See also: Perfect Guards
See also: Quintet Wall

"Sentinel" (守護者センチネル Senchineru) is a keyword used on Perfect Guard and Quintet Wall cards, and introduced in Booster Set 9: Clash of the Knights & Dragons. In Cardfight!! Online, Sentinel is indicated by a shield-like icon in the deck build;

How it Works

The "Sentinel" ability remains always active from anywhere, anytime. Therefore, even during the deck contruction, your main deck can only contain up to four cards with "Sentinel" ability using any combination, no matter what those cards have different card names.

Regarding Cards without Sentinel

All Perfect Guards that previously existed have been errated to have the "Sentinel" ability, which means you cannot have, for example, four Halo Shield, Mark and four Halo Liberator, Mark in the same deck, even if one of them does not have the "Sentinel" ability.