Mel vs Vel'Koz

Stay back and poke with Radiant Volley (Q): its projectiles explode in an area up to 950 range, and each hit applies Overwhelm.

Land an auto after each spell: Searing Brilliance (passive) adds three projectiles to it per spell cast, and enough Overwhelm executes the target.

Save Rebuttal (W) for a dangerous projectile: the barrier sends it back to its caster, and you gain a shield and move speed.

Hit your target head-on with Solar Snare (E): only the core of the orb roots, the aura around it just slows and damages.

Cast Golden Eclipse (R) to finish from range: it hits every enemy marked by Overwhelm, wherever they are, harder with each stack.

Get out of the line of Plasma Fission (Q) and watch its sides too: the bolt splits into two branches at 90 degrees when it hits a target or he recasts it.

Back off after taking two of his spells: at the third Organic Deconstruction (passive) stack, you take a burst of true damage.

If you can engage, go in after Tectonic Disruption (E): it's his only spell to push back someone charging him, and he has no dash to escape.

If you have a stun, a silence or a knock-up, save it for Life Form Disintegration Ray (R): any of them interrupts the ray.