Cybermen Squadron

Nonlegendary artifact creatures you control have myriad. (Whenever a creature with myriad attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)

Vault of Whispers

Mishra, Eminent One

At the beginning of combat on your turn, create a token that's a copy of target noncreature artifact you control, except its name is Mishra's Warform and it's a 4/4 Construct artifact creature in addition to its other types. It gains haste until end of turn. Sacrifice it at the beginning of the next end step.

Gloomlake Verge

{T}: Add {U}.
{T}: Add {B}. Activate only if you control an Island or a Swamp.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Undercity Sewers

({T}: Add {U} or {B}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)