Allies affected by your Astral Mark deal 15% increased weapon damage.
Reduce the Cooldown of Astral Mark by 0.5-2.5s.
Increase the duration of Astral Mark by 0.5-2.5s.
Increase the range of Astral Mark by 10-50%.
Increase the range at which you can use Void Grip by 10-50%.
Heal for 40-200 every 1s for 10s after applying Astral Mark.
If you're playing Jenos correctly, you should have the least deaths on your team, possibly the game (considering it's not one of those games the MMR completely drops the ball on).
Start every game by giving your first heal to your flank, even before they are hit-this will give them the 15% damage boost and an ultimately better chance of winning any encounters. After that, keep your attention on your teammates HP with a focus on the tanks.
Jenos can heal through walls, from quite a distance as well. Use this to your advantage by staying hidden from enemy sight, popping out every once in awhile to Void Grip an Evie/Maeve or lay some annoying cover fire on a Strix. If you get hit, pretty much at all, get away using your Stellar Wind movement ability.
Jenos Ultimate is highly effective against teams that stick together. I get the most satisfaction from Jenos' ult when you find the Imani that just spawned a dragon from hell! Try to aim for the squishier champions if possible, and always ult from behind cover as Jenos becomes locked in place for a second or two.
Now go out there and conquer those cosmoses, JENOS!