The way to play Xerath as a support carry is to poke the enemy laners constantly and try to get off your Dark Harvest proc with your Q

This will hopefully turn you into a scaling monster if you gather enough stacks.
^
Keep in mind. YOU ARE A SUPPORT. This build is for flexibilitys sake. Its cause is to replace your ADC IF he quits/ints or to eventually scale into a second ADC in Late game. Having this build does NOT permit you to steal farm or steal kills.

The only time to take kills is when the enemy is retreating and is outside your ADC's range.

Since you are using the sub-rune Cheap Shot in fights or during poke you should also try hitting your W or your E before poking with your Q

This is why he works well with ADC's such as Miss Fortune or Ashe, because the enemies can permanently be slowed.

Rylai's crystal Scepter works well with this since it slows the enemy making it easier to hit your abilities, proc your cheapshot and make it especially easy to hit your ult if you hit one of them.


The sub-runes Presence of Mind and Ultimate Hunter allow you to constantly have your Ult up in late-game and combined with the Elixir of Sorcery you can destroy the enemy team any time you feel like it (if you can hit your skillshots)

This is I believe everything special to this build. This is not to teach you Xerath this is to show Xerath players a nice build to try out. This build is very situational and should only be chosen against a bot lane that you can probably dominate.