It's an interesting topic that deserves its own thread:

Puresteel Paladin + Sunforger

Puresteel Paladin
Creature - Human Knight
Whenever an Equipment enters the battlefield under your control, you may draw a card.
Metalcraft - As long as you control 3 or more artifacts, each Equipment you control has equip 0.
2/2

Once the combo with Metalcraft active is established, you can fetch Seething Song and Manamophose for free draws and extra activations.

Current known ways to go infinite:

- Wheel of Sun and Moon is already in play enchanting you --> infinite draw + tons of mana, probably ending in a lethal Banefire

- Another variant involves: Skyshroud Elf, Emrakul, Firestorm and Eladamri's Call

Step 1: Get WWR from lands, activate Sunforger, grab a Seething Song
Step 2: Second activation, grab Manamorphose, add GW to your mana pool. (RRRRGW now in it)
Step 3: Third activation - get Eladamri's Call, fetch Elf and play it (RR left)
Step 4: Filter one mana into W, activate to grab another Seething Song, filter the mana, generate more mana by fetching mana sources.
Step 5: Use another Call to fetch Emrakul, grab Firestorm, discard Emrakul to it, shuffle your graveyard back (requires a Firestorm in your yard if you want to repeat the entire thing)
Step 6: Repeat generating mana and drawing cards until instant win (exact wincon debateable).

There might still be better combos out there. The best way to establish Metalcraft fast in a decent manner is also going to be an important topic.