If that creature is a Cat, it gains first strike until end of turn
You may cast Reckoner Shakedown even if you don't control any creatures or Vehicles
Like I already mentioned, I highly doubt well see dungeons and venture cards printed into the Standard rotation again soon
With a lid that clamps firmly closed thanks to Ultimate Guards patented ZnapClaw closure, the Arkhive is all you need to ensure your several Commander decks dont start clanking together in your backpack as you head to Commander night
For decks with three or more colors, where you might only be able to afford a small number of MDFCs since you'll need most of your lands to either be basics (for ramping / tutoring purposes) or tap for multiple colors of mana, the best MDFCs are Bala Ged Recovery (seriously, if you have green mana in your deck, play this card), Valakut Awakening, Hagra Mauling, and Ondu Inversion, along with the mythic cycle, which is almost always good if you can afford another land that only taps for a single color of mana