The grails are all promos and tournament prizes, so a trophy border or event card is the flag
Gamble could see play in decks that are looking for redundancy in their card search effects or want to take advantage of the randomness for a potential high-risk, high-reward playstyle
While the 4 drop price tag is a bit steep, Black decks in commander dont usually have an issue generating mana
Everything becomes exiled, and when the Portcullis is eventually destroyed, you deal another 10 damage
Quina, Qu Gourmet is another good way to get extra creatures, as it tacks an additional Frog token on to any other token creation that you do on your turn
The gold accentuates Ho-Ohs ethereal presence, and feels like an ode to the Pokmon synonymous with vibrant colours and rainbows