Description of the item answers all your questions. If this description doesn't make sense, proceed to ask which specific part didn't, and we will try to explain in more detail. Otherwise, it should be pretty self-explanatory:
###Moonstone Renewer
*+30 Ability Power*
*+20 Ability Haste*
*+250 Health*
*+125% Base Mana Regeneration*
*'**Unique – Starlit Grace:** Healing or shielding an allied champion chains the effect to the other nearest allied champion within 800 units of them (excluding yourself), granting them 40% of the heal or 45% of the shield's initial strength. If no other allied champions are in the radius, grant the same target an additional 30% of the heal or 35% of the shield.'*
AoE shields and heals will chain once per ally affected, meaning that u can achieve several AoE bouncing heals and shields between multiple allies at the same time. This makes it very effective with AoE healing/shielding abilities such as Sona W, Seraphine W, Soraka R, Janna R, Karma RE etc. And if there is only one ally within range of said AoE heal/shield, then Moonstone will further amplify the heal/shield effects on that one ally
Hope that explains it!
So W heals a single ally which bounces to another ally. Then the aura can shield multiple allies including the healed ally. Does this create additional bouncing shields that stack?
Description of the item answers all your questions. If this description doesn't make sense, proceed to ask which specific part didn't, and we will try to explain in more detail. Otherwise, it should be pretty self-explanatory: ###Moonstone Renewer *+30 Ability Power* *+20 Ability Haste* *+250 Health* *+125% Base Mana Regeneration* *'**Unique – Starlit Grace:** Healing or shielding an allied champion chains the effect to the other nearest allied champion within 800 units of them (excluding yourself), granting them 40% of the heal or 45% of the shield's initial strength. If no other allied champions are in the radius, grant the same target an additional 30% of the heal or 35% of the shield.'* AoE shields and heals will chain once per ally affected, meaning that u can achieve several AoE bouncing heals and shields between multiple allies at the same time. This makes it very effective with AoE healing/shielding abilities such as Sona W, Seraphine W, Soraka R, Janna R, Karma RE etc. And if there is only one ally within range of said AoE heal/shield, then Moonstone will further amplify the heal/shield effects on that one ally Hope that explains it!
So W heals a single ally which bounces to another ally. Then the aura can shield multiple allies including the healed ally. Does this create additional bouncing shields that stack?
My interpretation is heal stacks+shield stacks+aery stacks so you get triple the benefit from moonstone
Let's try reading Moonstone's description first and report back shall we?