Baldur's Gate 3

I think a trap a lot of players fall into in D&D is that in-combat healing is bad. Out of combat, sure, but during combat the better play 99% of the time is to do damage to the enemies, not heal your party.

Start thinking about how you can do damage with Clerics and you'll start to see the possibilities.

I respec'd her into Life Domain, then gave her the War Caster feat to help her concentration. Maxed Wis, put her Con to 16, and dumped STR.

For spells, use Beacon of Hope during combats where the party is going to take a lot of damage. It will maximize the amount they heal from her spells. Channel divinity and the Life domain spell list give you some fantastic options for keeping the rest of the party topped off on HP. She will get most of the healing spells from being Life domain, so you don't have to fret the selection too much. Do pick up Healing Word and Mass Healing Word, though. They can be used to heal at a distance and as a bonus action, which can be useful.

When it comes time to do some hurting, my picks were Spirit Guardians (OP spell), Guiding Bolt, and Inflict Wounds. Banishment also came in clutch to put fights with bosses on hold while I cleaned up the mooks or did some healing.

Life domain gives her proficiency with heavy armor, so... that. And a shield. I can't remember what items I've given her. Be on the lookout for things that either enhance her healing or give her healing a secondary effect, like granting Blade Ward for a turn.

Anyway, that's how I've built her, and it's worked well for me. I've only gone through the game on balanced, though. It's possible this won't work as well on tactician.

I did war cleric with war caster feat so she doesn't drop concentration. Let spirit guardians rip when you need to beat a fight.

Do tknow what you're talking about cleric is the strongest class in DND, even its worst subclasses will do well.

With Shadowheart, just grab spirit guardians, maybe some higher level summons. You can also grab some strong AoE spells if you want.

If you really want to change something for some reason, but want to keep her cleric, I believe tempest or war cleric also give heavy armour and help her be a frontliner.

What level are you? Cleric really shines once you get spirit guardians at 5th level, especially in Act 2.

Trying to heal more than the enemies deal in damage is very rough, though there are some good items in this game that make it more viable. But casting heals with your main action is still usually a waste.

If she's missing a lot, make sure to check hit chance before you attack. She's proficient in simple weapons at least so give her decent weapons and check if they have a better hit chance than her spells.

Life domain, war caster.

Bless staff from tower if you have other casters in your group.

Use Bless to start out every fight. Upcast as soon as you have lvl 2 slots to include all 4 main party members (including yourself will add 1d4 to your saving throws meaning you are less likely to drop the concentration).

Then use sanctuary as well if a tough fight.

Spirit weapon can be cast without losing sanctuary.

At 11, slot Planar Ally and choose Deva. Include it in your Bless to make sure fear smite hits.

Take a number of heal spells, and wear Zevlor's gloves.

Trivializes most fights, and Sanctuary + Life domain is very strong in keeping your party up.