I wish that if Red/Green was meant to be a secondary ramp archtype, we saw a bit more from Red than Horned Stoneseeker that pushed powerstones some for the deck, but Red is solid enough with some good creatures
While Karn isn't breaking anything and shouldn't be banned, if we ever get to the point where Karn, the Great Creator finds itself on the banned list (which is unlikely but not impossible), then Mycosynth Lattice would be 100% safe to unban
Those reactive cards need to have proactive elements, so that theres a real decision you can make instead of feeling like youre being forced to wait (which would be very un-red)
You need lands to make mana to cast your spells, so not having access to a base function of the game is rage-inducing while you watch everyone else play
Additional Variations 1
Theres a heavy historic matters theme throughout this deck, which means an emphasis on sagas, artifacts, and legendary cards