Massive Movement Speed mobility and scaling damage.
Improved attacks and sustained damage
Attacking and moving builds energy stacks. At 100 stacks, your next attack heals you and grants increased MS.
Takedowns restore 20% of your maximum mana and refund 10% of your ultimate's cooldown.
Takedowns on enemies grant permanent Tenacity.
Deal 7% more damage to low health champions. Gain AD/AP after kills or assists.
9% attack speed, 10 ability power or 6 attack damage
Gain 3% extra MS. Gain extra AP or AD, based on your bonus MS, Adaptive.
Gain increasing amounts of AD or AP, Adaptive over the course of the game.
The bonus Movement Speed paired with the Movement Speed from your evolved [Q] makes Viktor an incredibly slippery mid-fight mage. the extra bit of healing is also nice for sustaining in lane.
Presence of Mind can help you a lot in the early game to apply pressure with poke and spell spamming after leveling up.
None of the options here are ideal for Viktor, but the extra bit of Tenacity in nice, especially against champions who have a lot of lockdown CC.
Coup De Grace is the most reliable form of damage amp for Viktor as you'll often be building a Rylai's and will have more health than the enemy AD Carry/Support.
Celerity pairs nicely with evolved [Q] and Fleet Footwork to give a ton of Movement Speed mobility.
Gathering Storm makes you a late game monster, able to take over with your massive AoE teamfight damage.
Patch 8.10 saw a buff to Phase Rush and jungle duels for scuttle making Xin a powerhouse.