Okay, but why does the new mastery Windspeaker's not apply on the caster?

Your shields and heals on allied champions (excluding yourself) are stronger and increase your target's resistances for a few seconds

I honestly like this mastery, mostly because of the increase of resistances and the strenghts of the shields/heal, though why can't these bonuses apply also on the caster? is the fear of abuse cases too high? I can imagine riven/sion getting this mastery + the new mastery that increases heals/shields by 8%, and might outsustain everyone with their shields, but I'm just wondering. I've tried it out on the pbe servers, yet I don't see myself worth getting it if I can get Thunderlords on some poke based supports.

Will there be any changes in future for this mastery?