A support character who excels when on the attack and falls to pieces on defense, Zenyatta is the feeblest hero in Overwatch. He makes up for that extreme vulnerability with two abilities that can turn your own heroes into deadly killers or wither away all the strength of an enemy hero. If you fancy a high-risk-high-reward style support, Zenyatta is an interesting choice.
Orb Of Destruction [LMB/RMB] - Zenyatta makes up for his pitiful health points by packing a mean punch with his Orbs of Destruction. Each one does surprising damage when paired with his Orb of Discord ability, and you can hold RMB to charge up several orbs at once to really knock an enemy on their ass. When using the RMB charge attack, it's worth noting that each orb does less damage, but being able to fire them simultaneously will make up for that.
Orb of Discord [E] - This ability places a floating Orb of Discord on an enemy unit, increasing the damage they take from your team by 50%. You can only place one orb at a time, but you're free to move it around to enemy heroes as you please—just remember to mark a new target when one dies. There's also no limit to the range, so you're free to drop this on an enemy and head elsewhere on the map.
Orb of Harmony [LSHIFT] - The opposite of Orb of Discord, target an ally and tap LSHIFT to grant them this orb which will steadily recharge their health over time. Like Orb of Discord, there's no limit to the range, but you can only place this buff on one character at a time.
Transcendence [Q] - When this is active, Zenyatta becomes invulnerable and begins healing all allies within range. While this ability is active, you can't do anything but move around, but this creates awesome opportunities for hard pushes. Even better, the visual effect of Transcendence will often cause less experienced players to waste ammo shooting at you.
Zenyatta Strategy Tips
Zenyatta is both an incredibly easy and challenging hero to play. He's easy because none of his abilities require any skill beyond aiming at heroes and remembering to move your two orbs to new targets. He's challenging because he has the fortitude of single-ply toilet paper and anyone with a shred of experience in Overwatch won't hesitate to take the extra second needed to kill you.
That means you're going to be spending a lot of time hiding because, frankly, stepping out into the open as Zenyatta is stupid. You can risk it occasionally to get a few shots off, but more often than not any hero you go toe to toe with will destroy you.
Instead, focus your energy on cycling Orb of Discord to as many targets as needed. There's some on-the-fly prioritization that you'll need to be making, which can be difficult if you're playing in a public game and can't coordinate with your team. Just remember this, there's no point in putting the Orb of Discord on heroes like Widowmaker if your team is just going to focus on attacking Reinhardt. With that in mind, it's usually better to figure out what enemy hero is the target of your team and applying the Orb on them to bring them down that much faster so that your team will then move onto the next hero.
For your Orb of Harmony, you're going to want to balance using it to heal frontline heroes like tanks and putting it on offensive heroes to make them that much deadlier. For example, dropping the orb on Tracer will turn her into a formidable flanker who can aggressively harass the enemy without worrying much about staying alive.
Because both of these orbs are so passive, it's also easy to forget that they even exist. Dropping an Orb of Harmony or Discord and then forgetting about it makes Zenyatta virtually useless as a hero, so get in the habit of consciously tracking where both are at any one moment.
Finally, like many abilities, Transcendence is a fantastic way to push forward on the map. Because you're invulnerable while using it, put yourself front and center and lead the way for your teammates. The glow of your ability will often draw fire from your team, the whole effect is actually really distracting, and the psychological effect of knowing your team is getting massive heals will often cause enemies to back off entirely. Like Lucio's ultimate, dropping this during the final seconds of a contested match can be the difference between defeat and victory.