(3 Ideas for how this could work. #1)… (One for all.) puts down a circle shield thats just big enough for your team with (750 health) same as the gold knockdown shield. when you're in it legend "X" dont have a name for her yet. can use any shieldArmor or health item and it will be shared with the entire team. So let's say you're all at 30% health and there's only one Med Kit, give it to legend X, and now they can restore everyone's health.
(#2)… One for all lasts 20 seconds enough time for two Phoenix Kits. In that time any health items legend X utilizes will be shared with the entire team.
(#3)… Puts down a circular shield with 250 health. Can put health items in the circle whenever someone on your team needs that item. it will be used on them and only them. so they can focus on fighting.
example, place a shield cell in the circle, the Wraith on your team losses a shield (chunk?) that cell will then be used on her.
so put down (One for all) put some health items in it then start a fight. hope that made sense.
about the circle shield. there's a beacon in the middle of the circle. shoot that to end it. Or there's always a time limit. like 20 seconds and there's no way to end it before that time is up.
note. Legend abilities do not stack. so lifeline and Gibraltar. will not get increased healing in (One for all) however, if legend X has a gold body shield, the effect will work.
Source: https://www.reddit.com/r/apexlegends/comments/ewwk29/a_new_legend_ability_i_think_would_be_cool/