I think this would be game breakingly OP as all get out... but I think some of the ideas are a good start.
the passive is the main issue i have because having basic attacks heal allies MAAAYYYY be a bit crazy... build hurrican, censer, rageblade and that is one silly op damage boosting group healer without using resources or abilities. imagine if you can crit or lifesteal off of it... but with it having no restrictions it would be worse than soraka heal and mana botting under a tower without having to interact with the enemy. it would either need to have a massive drawback of super small/flat heal, draining health and/or mana, or some kind of mini-game component. a mini-game like when you attack a champion, or kill a minion you build charges, and for each charge you can AA a friendly champion to heal them, so its limited without having to have big draw backs while promoting interaction with enemy champions. OR it could be changed to an ability. maybe a toggle where you switch it on and you can only attack friendlies, kind of like how jinx's switcheroo, draining mana or health with each heal. or it could be a short duration skill like kayle's righteous fury but a long cooldown.
I DO like the idea of placing a orb and being able to amp up its power and effect, kind of like a tristana mixed with orianna... but what would set this skill apart from these other than it being weaker and a shorter cool down? seems like it steps on another characters toes... lets say this character has 2 modes/stances, damage and heal. setting the orb puts it at a 3/5 hp, so when you attack it in damage mode it pulses out small damage and a slow, and when you attack it in heal mode it pulses out small heal. if it dies, it implodes stunning and/or pulls things in, and if you heal it to full it explodes healing or shielding things around it.
to be honest the Q and R do seem a bit boring and OP... ahri AoE charm, and a 3 hit ranged xin zhao knock up. needs some kind of spice or interaction with the rest of the kit...
just some ideas for your idea.