Even on Magic Arena, a select few Alchemy cards conjure the cards to give you a chance to play a card like Tropical Island through Shoreline Scout, without the dual land becoming legal in Timeless
Green is already the color of explosive-yet-dependable mana acceleration via things like mana dorks and Gaeas Cradle, so if any deck could hand the rate of paying two mana per card then it would most definitely be a green deck
It's fine if a card can double its own counters, but they have to be able to double something else to make this list
You need look no further than Prophet of Kruphix, which is banned in Commander to this day, to see how powerful untapping your board additional times can be
The one iffy thing about the design is that it doesn't cost any cards to Escape
Grim Servant Tutor on a creature, based on devotion to black