That is to say, we're ignoring the Secret Lair decks (with all apologies to that one fan of Everyone's Invited )
It is one input among many, and hard floors from Game Changers or combo detection can override it
Landcycling for is consistently decent, despite the fact that Avatar: The Last Airbender has lots of exciting cards and this is on the low end
You may want to add in a few other Fog effects to make sure that people cannot gang up on you and swing at you multiple times forcing their way past his tap ability
If the Unearthed creature gets exiled by a different effect than Unearth, that effect will work as intended so if the creature gets put into an Oblivion Ring and then the ring gets destroyed later, the creature will come back to battlefield again as good as new, as if it had just been cast from your hand
Adapting your strategies to these new additions can give you an edge in competitive play