Overall jenos is a good healer that is a great pick for all maps, especially the biggest ones. Unlike other healers e.g. Grover, Seris etc... jenos cannot provide burst heals but only constant healing over time. For this reason, picking a jenos with champs that can self-substain such as Khan & Barik is usually a great set-up.

Picking jenos with other tanks that have plenty of hps such as Inara or Koa, is not always the best option since you're trading lower heals for a higher damage output. This is mostly the only negative about Jenos.

On the other hand he has lots of positives, making it one of the most sought-after champs in Paladins. First of all, he gives +15% in dmg output to whomever is being healed by him Astral Mark and that quickly adds up in a game! Secondly, he can heal through walls and has a pretty good range (especially when picking the Lightyears card at lv 5) making him very versatile.

Jenos movement together with its ability to "lift" enemies is also great as it gives you a high chance of always going back to safety whilst being flanked but also give you the chance to keep champions with no mobility "dash" (e.g. tyra, inara, vik, skye) easy to shoot at and negate others champs "dash" ability by lifting them (e.g. ash shoulder bash & ult, term jump).

Last but no least, Jenos ult is in my opinion the best ult among healers if not one of the best among all champions. The ult deals just enough damage to kill any flanks, healers, dps in one shot but also goes thorugh shields and such, hence dealing a pretty good 2.4k damage to frontlines. Using the ult in corridors or tunnels where enemies usually aggro often gets you at least an immediate double kill. Resorting to the ult, even thought requires perfect timing, can also be done to avoid being affected by others champs ults e.g. inara's or khan's.

One of the most important thing to keep in mind with jenos is that chronos 2 is obligatory to have a decent pace of healing and hence bringing a constant +15% dmg buff to some of your crewmates (and healing to yourself). Once chronos is taken, morale boost can be a great second pick as well as cauterize. If the enemy team has aggressive flanks then it suggested to grab heaven or blast shields instead of morale.

Staying alive as much as possible is a must with jenos, especially before getting to Chronos 2. It should be normal in a ranked game trying to die less than 5 times for every 20min.