Spectator Seating

Spectator Seating enters tapped unless you have two or more opponents.
{T}: Add {R} or {W}.

Krark-Clan Ironworks

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

{1}, Sacrifice a nontoken artifact: Create a 1/1 blue Thopter artifact creature token with flying. You gain 1 life.

Training Center enters tapped unless you have two or more opponents.
{T}: Add {U} or {R}.

When Imperial Recruiter enters, search your library for a creature card with power 2 or less, reveal it, put it into your hand, then shuffle.

Sundown Pass enters tapped unless you control two or more other lands.
{T}: Add {R} or {W}.

{T}: Add one mana of any color that a land an opponent controls could produce.

At the beginning of the end step, if you control no artifacts, sacrifice Glimmervoid.
{T}: Add one mana of any color.

Vault of Champions enters tapped unless you have two or more opponents.
{T}: Add {W} or {B}.

Whenever an opponent casts a spell that targets you or a creature you control, you may draw a card.

Haunted Ridge enters tapped unless you control two or more other lands.
{T}: Add {B} or {R}.