While Tiamats price has slid a bit from the high it reached during the new sets preview season, its still a solid $35+ above where it was at the beginning of March
If you already have an extensive Magic collection and already have a lot of the staples like Force of Will, you might be able to grab what you need for a Vintage deck without paying full price, but with how common the Power 9 and other Reserved List cards are in the format, it likely still wont be cheap
Youll have to watch out for board wipes, but otherwise your opponents will have a hard time handling your pack
This alone is not bad at all for MTG 's Commander format, be it casual or competitive, as Blue comes with a lot of good tools to counter opponents' spells, draw cards, and generally control the battlefield
Check the official card image gallery from WotC to see them all
\o/ P.S.: Which one you guys think it is better, Cautery Sliver, Acidic Sliver or Psionic Sliver