The Blue Build (name is obvious from the talent selection) seeks to turn Xul into a scary damage dealer, who can set up or execute kills. There is a good amount of defensive and offensive utility in Shackler at level 1, further talents will increase Bone Shield's uptime if you pick this talent at level 1. At level 16 you can pick Amplify Damage, which will help you set up kills for your team, but I personally like the high damage-low cooldown and mana free Bone Spear. This build is effective against multiple melee heroes, but is lacking against ranged, high mobility heroes.

The anti-heal build is the proper choice against team compositions that aim to outsustain and win by war of attrition, such as double tank-double heal comps. This talent set provides you with perfect waveclear (on a budget compared to the mana cost of Cursed Strikes), and allows you to keep a healthy distance from the fight. At level 16 Corpse Explosion or Bone Spear can replace Amplify Damage if you need more lane pressure, or enhanced ranged damage output (although this is a build your allies can capitalize on big time, so Amplify Damage is the quote on quote correct talent).

The Lane Pressure Build tries to enhance Xul's trait, by allowing you to create more, and better Skeleton Warriors. This build is not advised on two lane maps. At level 1 you can switch Shackler to any of the other talents based on your preference, but the provided slow further helps you with keeping up Executioner's damage increase effect. Both heroics are viable, but I prefer Skeletal Mages for their utility. Similarly both heroic upgrades at level 20 can be viable based on your team's needs. This build gives you insane lane pressure, and a very generous almost passive health and mana restoration - as long as you are laning.