Spatial Merging gets errata to read "Place both of them in the same slot on the planar map" instead of "Simultaneous planeswalk to both of them." My main guiding principle for these house rules was that phenomena are random, one-time events, so it was aesthetically unappealing to have them sitting in a spot, waiting to be triggered
Since it doesn't exile the tokens, you even have the option to do both to create a very threatening battlefield that can handle just about any situation
Vampiric Tutor Affordably priced at just one black mana for the ability to put any card at the top of your library, Vampiric Tutor is a phenomenally powerful card
Artifacts such as Contagion Clasp and its bigger sibling Contagion Engine let you invest mana into proliferate triggers, turning them into engines your opponents must answer
One mana turns into two the first turn you bring it into play, and then you just get two colorless mana every turn thereafter
Ooo I like Qarsi Deceiver, and I took out Jeering Instigator for the same reason I took out Thousand Winds