If asked for a favourite I'd have to say
Waste Not +
Words of waste +
Geth's Grimoire.
In your upkeep, trigger Words, when you go to draw, opponent discards. Trigger words again in response to Geth trigger, opponent discards again.
This gets really ugly in multiplayer. Whenever any opponent discards a land, you get free mana to get them to discard some more. Any creature gets you a 2/2, any non-land, non-creature gets you a card.
Even better if you can cantrip into it in your main-phase. Plenty of mana to finish up.