Most of your abilities (including your ultimate) have long and noticeable startup times. Torvald's Nullify will interrupt those, so wait until he uses it or buy Resilience to reduce the downtime he can cause.
Strix can heavily tip the balance of information in his favor. His flare can reveal you, and his stealth makes him harder to track down as well as giving him a free shot against you. Avoid direct confrontation and stay out of his line of sight.