There's a bug in the Brawl format legality warning in the deck builder. Brawl now has a special exemption for Command Tower and Arcane Signet - they're perpetually legal even if there isn't a standard-legal printing (see the WOTC format page). So there shouldn't be a warning when putting these two cards in a Brawl format deck. Can we get this updated? Thanks!

Fixing today, thanks for reporting.

sebi wrote:Fixing today, thanks for reporting.

Looks good now, thanks!