Whether youre building around Sauron, the Dark Lord in a powerful combo list or sleeving it up for a casual pod, having access to this card at a fraction of the original price opens up your entire deckbuilding strategy
If you leave the game, the effect giving you control of the target creature ends
In some ways, MTG is taking a leaf out of Pokemons playbook
Be free to break those rules and differentiate as you see fit, as many times special builds/decks require quite different approach and it heavily depends on your preferred playstyle, the chosen commander and the mechanics in use, among other things as well
Isshin, Two Heavens as One's ability affects only triggered abilities with conditions that are directly related to attacking, such as "whenever [this creature] attacks" or "whenever you attack with one or more creatures." It does not affect triggered abilities with other trigger conditions, such as "whenever [this creature] becomes tapped." Isshin's effect doesn't copy the triggered ability
The rulings on Goblin Game dont offer much guidance