You’re not getting past Zamir’s blockers anytime soon. Aside from the fact that he’s got two vigilant flyers in play where you have none, his Palace Guard is likely to block any creature rush. Your Zombie Assassin can certainly help out, but you’ll need to use it carefully, since you’ll only have the opportunity to use it once this turn.

One other option you have is to get the Scourge into your graveyard, then get it onto the battlefield via Search for Survivors. The problem is that Search for Survivors has a random effect: If you cast it, you might end up with a completely different creature. Or worse, you might end up with no creature at all. What you can also do, however, is optimize your chances.

1. Tap two swamps to add (one used as generic mana) and two mountains to add (one used as generic mana) to your mana pool.
2. Discard Faerie Macabre from your hand to activate its ability. Choose to exile Goblin Lore and Mountain from your graveyard. (You now have six cards in your graveyard: Crested Craghorn, No Rest for the Wicked, Mind Rot, Fountain of Youth, Nova Chaser, and Faerie Macabre.)
3. Spend , tap Undertaker, and discard Scourge of Valkas from your hand to activate Undertaker’s ability. Choose to return Faerie Macabre from your graveyard to your hand. (You now have six cards in your graveyard: Crested Craghorn, No Rest for the Wicked, Mind Rot, Fountain of Youth, Nova Chaser, and Scourge of Valkas.)
4. Discard Faerie Macabre from your hand to activate its ability. Choose to exile No Rest for the Wicked and Mind Rot from your graveyard. (You now have five cards in your graveyard: Crested Craghorn, Fountain of Youth, Nova Chaser, Scourge of Valkas, and Faerie Macabre.)
5. Tap and exile Zombie Assassin, and exile Fountain of Youth and Faerie Macabre from your graveyard to activate Zombie Assassin’s ability. Choose to destroy Zamir’s Shepherd of the Lost, so that Zamir no longer has any blockers with first strike. (You now have three cards in your graveyard: Crested Craghorn, Nova Chaser, and Scourge of Valkas.)
6. Spend to cast Search for Survivors. This results in your returning a random creature card from your graveyard to the battlefield (since all remaining cards in your graveyard are creature cards).
7. If Scourge of Valkas returns to the battlefield:
   • When Scourge of Valkas enters the battlefield, its ability triggers. Choose to have it deal 1 damage to Zamir. Zamir is now at 3 life. Since you now control a Dragon creature, your Bladewing’s Thrall has flying.
   • Tap Mogg Cannon to give your Kuldotha Flamefiend +1/+0 and flying until end of turn. Kuldotha Flamefiend is now a 5/4 creature with flying.
   • Declare the start of your combat phase, assigning your Bladewing’s Thrall and Kuldotha Flamefiend to attack. Since Zamir only has one creature with flying left (his Archangel), he is only able to block one of your attackers. Zamir’s best move is to block your Flamefiend with his Archangel, in which case your Thrall will deal 3 damage to him, defeating him.
8. If Crested Craghorn returns to the battlefield:
   • Declare the start of your combat phase, assigning your Crested Craghorn to attack.
   • When Crested Craghorn attacks, its provoke ability triggers. Choose to target Zamir’s Hornet Nest, and force it to block Crested Craghorn this turn.
   • Regardless of what other creatures Zamir uses to block Crested Craghorn, have Crested Craghorn deal 4 damage to Zamir’s Hornet Nest.
   • Hornet Nest’s ability triggers, causing Zamir to put four 1/1 Insect tokens onto the battlefield under his control.
   • Your Blood Seeker’s ability triggers, forcing Zamir to lose 1 life for each Insect token. Zamir loses a total of 4 life and is defeated.
9. If Nova Chaser returns to the battlefield:
   • When Nova Chaser enters the battlefield, its champion ability triggers. Choose to exile your Kuldotha Flamefiend.
   • Tap Mogg Cannon to give your Nova Chaser +1/+0 and flying until end of turn. Nova Chaser is now an 11/2 creature with flying.
   • Declare the end of your turn. You are forced to destroy Nova Chaser due to Mogg Cannon’s ability.
   • When Nova Chaser dies, return Kuldotha Flamefiend onto the battlefield under your control.
   • When Kuldotha Flamefiend enters the battlefield, its ability triggers. Choose to sacrifice your Mogg Cannon. This causes the Flamefiend to deal a total of 4 damage among any number of target creatures and/or players; choose to deal all 4 damage to Zamir, defeating him.