Power is the leftmost number, the amount of damage the creature deals in combat
However, Exterminate stands out as a brutal kill spell, especially effective if you have daleks available to tap
A slight tweak on the above included Auras that worked differently depending on what color of creature they enchanted
You look for mill-related cards like Mesmeric Orb or Mindcrank which can affect everyone instead of target opponent mill X cards. You may need very specific combos like Fleet Swallower with Bruvac the Grandiloquent, which mills all of a certain players cards
There are unbalanced Cubes on purpose: Players may design a 70% black cube for some reason and add the other colors in a smaller proportion, or design a cube thats mainly artifacts and colors that work well with the theme
And if it wasn't there, I had the option to submit a custom design to create it