Try Cho gath. Doran ring 2 health pot. Magic Null Cape on first back, build Banshee Veil if ahead (AP) Spirit Visage if behind (Hp and regen buff) Both offer Magic Resist. If Syndra can Q you you should be able to Q her. Figure 8 pathing patterns do well on dodging her q, her w, and make her landing her stun difficult and if she does it makes less difference since you've been walking around her other spells. Do this off of your minion wave so her spells don't hit your creeps regardless. Make her moves miss you and the wave.
A solid q landing leads up to you walking up and auto'ing with a Feral Scream. Thunder Lord with Ignite available and you win the trade/have potential to finish. Rinse , repeat, sustain off Doran and Cho's Passive. As soon as you hit lvl6 (save up mana for this while you're lvl5) immediately go for a Feast execute. If you can't, don't waste time not feasting on a canon creep to get your stacks going.