iirc, heal can't have aoe attached to it, so I think the best thing you can do is probably something that creates multiple projectiles and/or uses pierce as a base
#AOE HEal?
tall timber
something like 
Fill up the rest of the space with more however many amplifies you want on the heal and more splits
snow fractal
Or set up a basic heal glyph spell and carry a jar of source around. Then once everyone needs healing have a spell to make a small box to protect you and drop the jar and make a rune and hit it with chalk.
Instant healing room
tall timber
That's... not really what was being asked for.
Orbit split... heal is technically aoe in a very small area around you
echo shuttle
tier 3 has linger heal?
snow fractal
Lingering heal would be a better solution also if any zombies walk into it they get damaged as well lol
tall timber
I would have suggested that, but I can't remember if Linger was added to 1.18.2
snow fractal
Yes
echo shuttle
tier 3
thorny fractal
Lingering heal would be a better solution also if any zombies walk into it they ...
cant find
tiny osprey
proven kiln
I would have suggested that, but I can't remember if Linger was added to 1.18.2
Linger was actually in 1.16.5, at least last I checked anyway
snow fractal
Yeah Lingering Heal is just a Projectile -> Lingering -> Heal spell
void rose
What I might see as useful is if it's more of an open area, have some 
, you can always just retreat and walk over the placed runes, for anyone. It's also very funny if you play with an open unlit base, and watch a zombie just walk over it and instantly die
delicate wren
Yeah Lingering Heal is just a Projectile -> Lingering -> Heal spell
Is Linger Heal worth it? How many ticks of heal do you get from it
snow fractal
Its basically you heal as long as you stay in the cloud. You can add extend time glyphs to the lingering glyph to keep it around for longer periods.
void rose
It's reasonably worth it, suggesting it's meant to heal multiple people, so I'd say more than 2 would make it properly cost effective guarenteed