Strange. I picked the real aatrox and even this version of him as a counter to trynd. Then again, you outscale him. I can safely say that if you want to beat him, then you just need to wait for your opportunity. Go in on him after he has used his Q's, spin out of his w (sideways or diagonal if you can) if you took a bad trade. His ultimate is probably the one thing that can mess you up since it can counter yours if played right. Vise-versa. My suggestion to you is to take advantage of the fact that he is now a spell caster and so if he misses those spells, then you bully him. Ignite in lane can also work to deal with the life steal. On a final note, since he now benefits more from building tanky, it's best that you be wary of how much time you put into these trades since reinforcements could be nearby.
P.S. I don't play much of trynd but I know my stuff when it comes to my Darkin.