This build is what i personally use for playing my main valla and work simply by using your q multiple time to strike down enemies and keeping your health bar full

For your ult i usually take the arrow rain because it gives the posibility to stun enemies that run away or to control a large amount of enemies to escape or iniciate combats and team fights.her first ult is a great idea as well because it does more damage im general as long as the enemie team dont have many heroes that can stun

The only great consecuence is that constantly shooting q and e will dry your mana pretty fast so the restoring wells are going to be important to keep your mana up