Predecessor Builds > Serath > Serath Damage Overload
With this build you go on full attack speed + lifesteal. You will be very squishy, but the damage (especially with ult activated) will be unreal.
Judgement is number 1 choice for additonal damage + heal. In the beginning keep up your farm and gank only when there is the opportunity to. As soon as you have your first two core items + ult you can erase enemies in seconds. Keep your E for Escape or if you are certain you get the kill. Terminus 3rd or 4th item is great for lifesteal. If you need anti-heal throw out Draconum and build Tainted Trident ot Rounds. Rounds allows for interesting combos with crit. You can also throw in e.g. Onixian Quiver as it provides nice damage mitigation. If you are against cc heavy teams use absolution, if you feel like you need more sustain take Salvation. For enemies that are nuilding armor you can use Basilisk or Demolisher. The latter also allows for some nice crit combos, e.g. if you build after your first 2 items Rounds, Terminus, Quiver and Demo you are already at 80% crit. One R + RMB and few auto attacks and basically every enemy will fall. Jump on squishes and then take out the tanks. GGs!