As mentioned last week, Shattered Pixel Dungeon's upcoming Cleric hero has a variety of unique spells which they can access via their holy tome. The first of the Cleric's spells is a simple supportive ranged option: Guiding Light.
Guiding Light is an innate spell (no talent needed to unlock) and does some damage while 'illuminating' the target. This guarantees that the next physical attack made against that target will hit.
(Image Description: a short GIF showing off the guiding light spell. The Cleric casts it on an enemy, which begins to glow. The Cleric then waits for the enemy to approach, and attacks them.)
Yeah, unfortunately it's just not really feasible to add. The whole game is designed around one player and lots of things would break or not play well, and that's before the trouble of adding networking code.
Mangband is a realtime multiplayer modification of Angband that forced turns every N amount of time, and while it is playable, yeah, I don't think that straight multiplayer conversions of traditional roguelikes work well.
Someone who wanted to try to do a "multiplayer traditional roguelikes" ' would probably need to make a number of game design changes at a pretty fundamental level to make the thing work well. Really a new game.
There are some multiplayer roguelites out there:
https://old.reddit.com/r/roguelikes/comments/auzail/best_coop_multiplayer_roguelikes/
That might kinda be something that the parent poster would be interested in.
Yeah Mangband is a good example of why I don't think this would work for Shattered.
If there's ever any sort of mutliplayer it would probably be more minimal or asymmetric, such as two players playing separate games of the same dungeon, but are able to pass items to each other.
That could be cool as a sort of competition, players would have to balance speeding ahead of the other player to find better items with not getting so far ahead that the mobs are too strong for them to handle.