So do I use health potions for ther entire game as a harbinger?
Currently level 15, on my way to Athens, and I seem to have to use potions the whole time, when do I find gear that lets me regenerate health|? Do I need to buy it from a merchant? I am follwing the harbinger build guide, any other tips you can provide?
Use trance of convalence it'll improve suitability and used in conjunction with viny growth will cut down need for health pots to
Potion use is high for most melee toons initially. As you find better gear and specifically weapons with Attack Damage Converted to Health as a bonus, potions usage will reduce until, by late Legendary, you should only be taking one occasionally.
Also look for the Ankh of Isis and Hermes' Sandals relics. Isis gives you health regen, can be put on jewellery and can spawn with an elemental resistance which is useful. Hermes is a movement relic for leg gear which can spawn health regen as its bonus. Isis is equipable from Level 12, but you won't find it until you get into Act 2 if this is your first play through; Hermes is a Level 3, but will only drop if you have the bugfix fanpatch installed (I definitely recommend installing it).
Gear wise look for green Juggernaut's (L15) body armour, ".... of the Glade" (L11) for arms/legs and Hallowed, Exalted (both L15) and "... of Stability/Solidity" (L3) for headwear. All of these give different sorts of health regen. Some blue/purple items also will later on in the game.
For weapons look for "... of Feasting/Devouring" as these give the Attack Damage Converted to Health that Irma2 suggests. You could also socket these with an Anubis' Wrath (L12 Act 2) relic which will add more ADCtH.
Vinyl Growth is the best charm for health regen as that is all it does, especially if it spawns with an additional health regen bonus, but hopefully if you can find the right gear/weapons and use Trance of Convalescence you won't need to use it. It's a L18 item, but an Act 3 charm so it's going to be a while before you can look for it.
All gear/weapons can either drop or be shopped for. Relics/charms only drop.