Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Mana Tithe

Counter target spell unless its controller pays {1}.

Puresteel Paladin

Whenever an Equipment you control enters, you may draw a card.
Metalcraft — Equipment you control have equip {0} as long as you control three or more artifacts.

Stoneforge Mystic

When Stoneforge Mystic enters, you may search your library for an Equipment card, reveal it, put it into your hand, then shuffle.
{1}{W}, {T}: You may put an Equipment card from your hand onto the battlefield.

Ancient Den

Sigarda's Aid

You may cast Aura and Equipment spells as though they had flash.
Whenever an Equipment you control enters, you may attach it to target creature you control.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Lurrus of the Dream-Den

Companion — Each permanent card in your starting deck has mana value 2 or less. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Lifelink
Once during each of your turns, you may cast a permanent spell with mana value 2 or less from your graveyard.

Steelshaper's Gift

Search your library for an Equipment card, reveal that card, put it into your hand, then shuffle.

Inkmoth Nexus

{T}: Add {C}.
{1}: Inkmoth Nexus becomes a 1/1 Phyrexian Blinkmoth artifact creature with flying and infect until end of turn. It's still a land. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Plains

Colossus Hammer

Equipped creature gets +10/+10 and loses flying.
Equip {8} ({8}: Attach to target creature you control. Equip only as a sorcery.)

Ornithopter

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Urza's Saga gains "{T}: Add {C}."
II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Mishra's Bauble

{T}, Sacrifice Mishra's Bauble: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.