Imposing Grandeur

Each player may discard their hand and draw cards equal to the greatest mana value of a commander they own on the battlefield or in the command zone.

Blades of Velis Vel

Changeling (This card is every creature type.)
Up to two target creatures each get +2/+0 and gain all creature types until end of turn.

Majestic Genesis

Reveal the top X cards of your library, where X is the greatest mana value of a commander you own on the battlefield or in the command zone. You may put any number of permanent cards from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Stinging Study

You draw X cards and you lose X life, where X is the mana value of a commander you own on the battlefield or in the command zone.

Hellkite Courser

Flying
When Hellkite Courser enters, you may put a commander you own from the command zone onto the battlefield. It gains haste. Return it to the command zone at the beginning of the next end step.

Karrthus, Tyrant of Jund

Flying, haste
When Karrthus, Tyrant of Jund enters, gain control of all Dragons, then untap all Dragons.
Other Dragon creatures you control have haste.

Descent of the Dragons

Destroy any number of target creatures. For each creature destroyed this way, its controller creates a 4/4 red Dragon creature token with flying.

Cloudkill

All creatures get -X/-X until end of turn, where X is the greatest mana value of a commander you own on the battlefield or in the command zone.