Your tables might be different, but Armageddon seems like it'll just make you a target for hate. Plus, you don't have that many mana rocks or alternate means of mana generation after casting it.

My experience with Angel Tribal is that Reya Dawnbringer is a trap; she's almost always a dead card, and even when you can play her, she's a massive hate target AND insufficiently impactful.

Cosmos Elixir is, IME, too low impact. 2 life per turn is almost nothing, and the card draw only triggers if you're already in a very dominant position. If you really want to keep it, try finding some more trigger-on-lifegain (like Archangel of Thune or Angelic Accord) - and even then, I'd recommend Authority of the Consuls instead, since it'll gain you more life AND slow your opponents down.

In addition to Deafening Silence, I'd recommend adding a Rule of Law, just for the added consistency of keeping the tempo of the table moderated.

Good luck!