Make sure the deck list is sorted by "Custom" to see each category
Over the past few weeks, I'd gone over Chulane, Teller of Tales, Korvold, Fae-Cursed King, and Alela, Artful Provocateur, in that order
The key is to remember that this is going into a deck that is running Black
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
If it's the second time, each opponent loses 2 life
This is especially important if the card is connected to any kind of interesting origin story (like most of the cards above)