I am building a Tiefling Dragon Sorcerer for a one shot and the DM has told everybody to choose a legendary item. I am looking at the Dragon Masks from Hoard of the Dragon Queen.
I have chosen Blue as the colour of my dragon ancestry and at level 6 i get the ability to spend a sorcery point to gain resistance to lightning damage. My question is, in terms of resistance and immunity, if i chose the blue mask, I would have permanent resistance to lightning from the mask, but would i get immunity by spending a sorcery point?
I am aware that resistance does not usually stack into immunity however the masks specifically call out:
You have damage resistance to lightning. If you already have damage resistance to lightning from another source, you gain immunity to lightning damage.
My question specifically comes from the fact that it says if you already have it. If i gain it whilst already wearing the mask then what happens?