Signature Spells Fails to Seek
Was playing a game in which I had out 'Signature Spells' - it did not seek during upkeep at all. Meanwhile, opponent had out a Liara of Flaming Fist. During the next combat its activated ability triggered to give a creature double team even though no mana had been paid. I lost the game because of this.
I also have had this issue in Brawl. Signature Spells fails to seek completely or only seeks one spell. I will try to get the log attached if it happens again,
Historic Brawl, specifically. Unusable without the enters trigger.