Door of Destinies won't trigger on token humans, but ought to see enough castings to get a few charge counters and become a problem for my tablemates if it sticks around for a few turns
You can see my upgrade article for Reap the Tides here, and Kristen Gregorys article for Arm for Battle here for some inspiration
In my opinion, it requires too much support to really pop off, and we just dont have the ability to do that in Limited
Cube is a mostly unsanctioned format aside from the Magic Online Cube and various events like the Players Championship using the Magic Online Cube and sanctioning Cube through the WPN network (but even then, thats only really for casual Planeswalker Points)
Its powerful, but dont be fooled into thinking you dont need to put the work in to reap the rewards
Lower mana cards that hit harder than you would expect for their value are ripe for banning in this format