It isnt hard to reach seven mana in Magic, particularly in control and ramp decks, so getting it out ahead of the curve is going to be a common occurrence
1 Fire Elemental
it would basically require Evolutionary Leap, Hangarback Walker, and a ton of other additional resources and mana to mitigate her abilities
At the beginning of your next upkeep, pay
Protecting these Creatures will be important, too, so consider some cards which can be sacrificed for protection purposes, such as Selfless Spirit or Boromir, Warden of the Tower (and of my heart.) You can also slow your opponents down with cards such as Blind Obedience, forcing their Artifacts and Creatures to enter tapped (this was a nightmare at CommandFest during AdamTheGatherings Wheel of Misfortune event) and Dragonlord Dromoka, which stops opponents casting spells on your turn, allowing you to get some big plays in before they have a chance to counter anything
Ghave, Guru of Spores Ghave is a fun Commander, and another that benefits from proliferate