This dot is extremely difficult to replicate accurately
And WotC has, in the last five years, made an effort to make sure each of their many Magic games receives enough pieces
They are best in the more creature focused ones for the obvious crew reasons
Outpost Siege is certainly the best at generating resources, but this deck does not have anything in the late game as powerful as Soulfire Grand Master loops, and I doubt Outpost Siege reverses the arrow of inevitability in our favor, so I favor something aggressive
Most of an Opt for not-necessarily-Blue mana
Bonus sheets from previous sets sometimes have a unifying mechanical theme (in Outlaws of Thunder Junction , for example, all the cards from the Breaking News bonus sheet could commit a crime), but there's no specific mechanical thread connecting these Through the Ages cards