Sojourner's Companion

Affinity for artifacts
Artifact landcycling {2} ({2}, Discard this card: Search your library for an artifact land card, reveal it, put it into your hand, then shuffle.)

Loxodon Warhammer

Equipped creature gets +3/+0 and has trample and lifelink.
Equip {3}

Ethersworn Sphinx

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card with lesser mana value. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Void Rend

This spell can't be countered.
Destroy target nonland permanent.

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Assert Authority

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Scourglass

{T}, Sacrifice Scourglass: Destroy all permanents except for artifacts and lands. Activate only during your upkeep.

Darksteel Citadel

Broodstar

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
Broodstar's power and toughness are each equal to the number of artifacts you control.

Dismantling Blow

Kicker {2}{U} (You may pay an additional {2}{U} as you cast this spell.)
Destroy target artifact or enchantment. If this spell was kicked, draw two cards.

Chromescale Drake

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When Chromescale Drake enters, reveal the top three cards of your library. Put all artifact cards revealed this way into your hand and the rest into your graveyard.

Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact you control.
When Emry, Lurker of the Loch enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Mistvault Bridge

Mistvault Bridge enters tapped.
Indestructible
{T}: Add {U} or {B}.

Metallic Rebuke

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Counter target spell unless its controller pays {3}.

Nettlecyst

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each artifact and/or enchantment you control.
Equip {2}

Thoughtcast

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.

Reverse Engineer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Draw three cards.

Thought Monitor

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Flying
When Thought Monitor enters, draw two cards.

Lens Flare

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Lens Flare deals 5 damage to target attacking or blocking creature.

Tezzeret, Master of Metal

+1: Reveal cards from the top of your library until you reveal an artifact card. Put that card into your hand and the rest on the bottom of your library in a random order.
−3: Target opponent loses life equal to the number of artifacts you control.
−8: Gain control of all artifacts and creatures target opponent controls.

Frogmite

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)