Healing/Support dungeon/pve build?
Well the very famous bunker support build can easily fulfill this role: 0/0/10/30/30. I suggest you try apothecary gear, I have not tried it myself but in theory this would be a good response to what you intend to do.
Retired elementalist theorycrafter
Apothecary gear is kinda useless IMO. Especially if he’s going to be doing this mostly in pve in dungeons. If you have anyone else in your party who isn’t an ele and actually can apply a decent amount of conditions and do good damage with it, like a necro, the little bit you do will be meaningless. You’re better off using cleric’s armor and zerker accessories. You’ll heal decently and still atleast be able to do some damage. There’s a limit to how many stacks you can throw on things, and if you’ve got anyone else in the party who is a condition build, you’re next to useless. I’m pretty sure a necro can easily cap 25 bleeds on a target alone, making our earth useless. Unless you just plan on spamming burns on things.
Yes with a minor in condition you should apply near perma burn and a bit of bleed. This gives you about as much dps as someone with a major in power only (traits ignored). It is true that some classes can easily fill the condition stacks, but when they are most optimal they will usually stack it up to 20, leaving you some room for a bit of damage. So it requires some group coordination, but it enables to heal while contributing a little to the damage output of the group. I am not saying that this is an optimal choice, but if he is going to do healing this is the best response I can think of. If he went for direct damage instead of condition like I advise, it would cost him more resources, so less healing.
Retired elementalist theorycrafter
My personal advice would be to not focus on support, but rather let it be an equal part of your build. However, if you really want to focus on it, you could try something like Rune of Altruism in combination with other boons. Also, if you use a staff, you can make use of the combo fields to buff your allies.
This is the build that you’re looking for.