personally for helix i’d go right at level 2 so you can decimate minion waves even more quickly(as well as any enemy battleborn that catch the mortars)
and I take the extra battery at level 5 ONLY if there’s another healer(38 hp/s may not be much but it’s better than nothing)
for level 6 it depends on if enemies are focusing your rifts. if they’re not focusing them go for the fourth rift because it REALLY adds some more power to your tankiness/destroying anything that wanders in
at level 7 I’ve fallen in love with bouncy mortars
at level 9 I actually normally take the pulse time upgrade as well if my rifts aren’t being hard focused.
for gear I’ve tried a few loadouts but i’m still testing some of the legendaries to see how well they work, and I often mix and match the options and they work well all around for me.
kleese’s lore legendary is absolutely gorgeous because it turns 10% of shields restored to allies into health for you, if you get a full rift network up(4 rifts) it will take
plasmite transducer is amazing because it turns 5%(at max roll) of damage you take into shards)
the Lorrian skill spike is an item that gives skills a 7% chance to deal 50% bonus damage. this means each individual tick can deal up to 50% bonus damage)
and the final one is chrono key(personally kleese doesn’t really NEED it but I love turning damage into cooldown time)
and if you have voxis core it makes all your skill deal 15% of the damage to enemies near the one who got hit by the skill.
if you don’t like legendaries then I would say shield strength and skill damage should be your priority over anything else.