@terminusz, the only "mass x" spells that i know of are through my mod, https://itch.io/t/492874/minor-tweaks-mod-v13-for-0524c-or-aricsexpansion522b
tldr - you can use it at mansion, not in combat or travel party
As it says in notes there,I reference the file to affect if you wanted to do that yourself (for travel party, very easy, combat not sure) but it prob wont be in any official release since it risks breaking compatibility with other mods too much.
Its really just a mid-end game helper, bit too OP for combat anyway, normal heal works great there and combat easy enough as it is once you reach mid-end game.
And thanks for spotting the spell description, i changed it quickly in my local version, so whenever i update it'll be even clearer.