1 Opportunity
This is a minor bonus with Dungeon Crawler, a moderate bonus with Precipitous Drop, a major bonus with Nadaar, Selfless Paladin, and worthless if you have nothing that cares about completion
No, transforming a creature doesnt remove it from combat , unless its exiled and then brought back like with the flipwalkers
Instead of trying to close out the game as quickly as possible, you would use Life from the Loam to ensure you can keep recurring your Bloodghasts and flashing back your Faithless Looting, while building a sizeable hand size to set up a big Conflagrate either to point at your opponents face or wipe out all of their creatures
In multiplayer Commander, broad removal spells like Farewell or Austere Command often clear the board of mana acceleration
Invasion of Mercadia / Kyren Flamewright With any list, there needs to be a last-place entry, and Invasion of Mercadia is the entry here