This champion mastery guide lists all of the masteries available and provides the description of each mastery and how to use them to build your champions based on a specific role! You can only activate 2 mastery tree and select up to 15 masteries from either trees in a descending sequence. There are 3 mastery tree types, which are Offense, Defense and Support. Hope this helps.Champion Mastery also known as Talent Tree can be customized for every champion in Raid Shadow Legends. Remember that farmign brutal campaign for 5 star peices with the correct sets and main stats is a great way to build champions in the early game. It's all about the mainstats to get him in a good build. And to answer your question directly, yes lifesteal set is the perfect set for him. But I would definitely add more accuracy as that is quite low. Then add more hp, defense if he dies too early in clan boss or dungeons, or add crit damage if you feel he sustains well enough.

Since his a2 (which is the only important skill that needs to crit) has an extra 15% chance to crit. If you need kael in a hybrid build where he needs to be good everywhere because you are early game, drop his crit rate to around 85. Sorry, I dont know what stage of the game you are in so I can't tell you how much accuracy you need for whatever clan boss you are on. Yes, an accuracy banner will give around 65 accuracy, but you want to be at around 150 for midgame clan boss. Looking at your stats, his accuracy is too low to land his poisons in most areas of the game, even early level so you definitely need more accuracy for clan boss.

If you already have a arena nuker and campaign farmer than build him with defense and accuracy for dungeons and clan boss. If you don't have a campaign farmer or arena nuker and have better poisoners then build him with crit rate and crit damage.

Now I am not sure how far you are into the game, but build kael for what you need. Kael can be rather tricky to build in the early game simply because he is so versatile everywhere.

Best gear for kael raid shadow legends