The obvious route would involve destroying Nathalie’s Suspension Field to get back your Abomination of Gudul, then reanimating the Mardu Shadowspear next turn. But that would only get you 4 damage, which wouldn’t be enough. Now if you could get that Noxious Dragon in your library to attack, then you’d have more to work with… but you would still need to find a third source of damage during your turn.

1. Before Nathalie’s turn ends, tap one island to add (used as generic mana), one swamp to add (used as generic mana), and two forests to add (one used as generic mana) to your mana pool.
2. Spend to cast Sudden Reclamation. Put the top four cards of your library (Noxious Dragon, Grim Contest, Monastery Siege, Swamp) into your graveyard. Choose to return Swamp and Mardu Shadowspear to your hand.
3. Allow Nathalie to end her turn. Your turn begins, and you untap all permanents you control.
4. At the beginning of your upkeep, Kheru Lich Lord’s ability triggers. Tap two islands to add (both used as generic mana) and one swamp to add to your mana pool. Choose to spend to return a random creature from your graveyard to the battlefield.
5. Because Noxious Dragon is now the only creature card in your graveyard, Kheru Lich Lord returns it to the battlefield with flying, trample and haste.
6. During your draw step, draw Thornwood Falls.
7. At the start of your first main phase, play your Swamp.
8. Tap one forest to add (used as generic mana) and one swamp to add to your mana pool.
9. Spend to pay Mardu Shadowspear’s Dash cost, putting it onto the battlefield with haste.
10. Declare the start of your combat phase. Assign Noxious Dragon and Mardu Shadowspear as attackers.
11. Mardu Shadowspear’s ability triggers, forcing Nathalie to lose 1 life. Nathalie is now at 6 life.
12. Nathalie may block Mardu Shadowspear with any of her four untapped creatures, but is unable to block the Noxious Dragon. Noxious Dragon deals 4 damage to her. Nathalie is is now at 2 life.
13. At the beginning of your second main phase, tap one forest to add (used as generic mana) and one swamp to add to your mana pool.
14. Spend to activate Qarsi High Priest’s ability, sacrificing Noxious Dragon.
15. Noxious Dragon’s ability triggers, allowing you to destroy a creature with converted mana cost 3 or less. Choose to destroy Nathalie’s Smoldering Efreet.
16. Smoldering Efreet’s ability triggers, dealing 2 damage to Nathalie and defeating her.