You’ve got a lot of restrictions to work around. First of all, you can’t win via combat damage ― you’ll never make it past your draw step. Second, you can’t win via damage at all: Tiberce can prevent quite a bit of it via Auriok Replica and Nim Deathmantle. And that’s not even counting the Platinum Angel that you can’t kill properly, not as long as the Deathmantle remains in the equation.

With that said… who said that you needed to kill the Platinum Angel? Wouldn’t you just need to, say, remove it from the battlefield?

1. At the beginning of your upkeep, Jinxed Choker’s ability triggers.
2. Tap two plains and Forbidding Watchtower to add to your mana pool.
3. Spend to cast Harm’s Way, choosing Jinxed Choker as the source. Choose to redirect its damage to Aura Thief.
4. Allow Jinxed Choker’s ability to resolve. The 2 damage from Jinxed Choker is dealt to Aura Thief instead, killing it.
5. When Aura Thief dies, its ability triggers, giving you control of all enchantments. You gain control of Blind Obedience.
6. Tap Intrepid Hero to activate its ability, destroying Platinum Angel.
7. Tiberce may pay at this point to activate Nim Deathmantle’s ability, returning the Angel to the battlefield. If he does, the Angel returns to the battlefield tapped due to Blind Obedience.
8. If Tiberce returned Platinum Angel to the battlefield, spend to cast Cloudshift on Surrakar Banisher. Banisher goes to the exile zone, then returns to the battlefield under your control.
9. When Surrakar Banisher enters the battlefield, its ability triggers. Choose for it to return the tapped Platinum Angel to its owner’s hand.
10. Spend to cast Intervention Pact, choosing any source.
11. When you cast Intervention Pact, choose to spend for the Extort ability on Blind Obedience. Tiberce loses 1 life and you gain 1 life; Tiberce is now at zero life and is defeated.