my low-elo ass warden build

Warden is an excellent harasser in lane, since his Flask can reduce stamina and his 3 can punish enemies using all of their stamina to reposition
It forces the enemy to play defensively, which is exactly where you want them.

Maxing 1 first ensures that your harass has high uptime
Combo'd with Quicksilver Reload makes for a very annoying, very consistent amount of damage you can toss while also letting you continue to poke at them with your gun
Healing Booster and Healing Nova further reinforces you and your teammate's survivability making it difficult for them to flip the situation on you.

By this point in the game you're a very potent supporter with a loadout that both keeps your teammates alive and makes you one very annoying rodent to deal with
Grab boxes and vending machines while traversing the map and look to gank other lanes.

Magnum enhances your gun, Escalating Exposure is valuable on your ultimate, and Vortex Web rounds them up
Healing Tempo amplifies the effectiveness.

Abrams can be an oppressive match-up due to his sustain, good close-quarters combat, and a powerful movement+CC ability
Build early to prevent snowball.

Spirit for raw power, T
Cooldown for your items, and Scourge to become an even greater menace to ANY who thinks they can take you and your ult on.

Build Resilience as needed, others depending on the enemy composition.

This should not be your priority, and as such only build if you need to diversify or require their special effects.