end of combat is the triggering event: the end of combat step has begun
This is neither mana ramp nor mana acceleration, but is a critical part of how white interacts with lands as it helps ensure you dont miss a land drop on your turns
If the Commander player base is only recently getting over its collective fear of Zur, this menacing demigod is likely to bring those old nightmares back at full strength
It immediately becomes one of the best protection spells in the format, while also offering yet another way to break parity on board wipes and nasty spells such as Armageddon
Sure, you want to save vampires to come onto the battlefield for free when Strefan, Maurer Progenitor attacks, but casting vampire spells with Bloodlord of Vaasgoth on the field can be a good way to buff your vampire army mid-game
It makes certain avenues of all-in or race style strategies pointless where they are typically one of the best things to do against something you can't deal with and will ultimately beat you