In the lane phase use W to stun when you got full-stack after that aa once E and Q with full-stack then back off. you can make a quick kill if enemies got about 50% health use W when 3 stack aa once E and Q this give you a quick kill. Keep in mind that your Q passive "damage increased against enemies below 20% of their maximum health" make sure you use Q at full stack and enemies health under 20% to make sure you can take everything from your adc. throw Q when dark harvest mark spear to stack it as much as you can. Try to kill someone that split push with W full-stack aa E and Q.You can press E again to make a quick shield bash.If you snowball try to camp in bush use W with full-stack aa Q and use E with full-stack to run away as fast as you can try tp throw Q when enemies health down 20% or if you really strong at that moment you can throw Q at 50% health.
here is a trick when you got a full build your Q is stronger than smite you can throw Q to steal baron or elder by using ult to go behind baron camp make sure you got the vision there to see baron health hold your Q when baron health = 3500-4000 then throw your Q when it comes about 1500-1700 to steal baron because your Q passive work on baron too.