As Purify has become a targetable spell with 1.30, one won't be surprised to see it interact with Emerald, Jade, Reflecting and Mirror Shield. I had this situation already twice but the results were incompatible.
- Scenario 1:
I have a Reflective Shield on my side and decide to use Purify on myself. After targeting my own HP bar, I see my shield sparkle as if it reflected a spell. However, I'm happy that Purify got indeed cast as intended and wasn't redirected to my opponent. Sorry, I forgot to take a screenshot of this but I clearly remember the +2 counter on my side. - Scenario 2:
The AI has an Emerald Shield up and uses Purify on itself. The shield sparkles and the spell gets redirected to me, the respective counter appears next to my HP bar (thanks AI). Moreover, the AI does that multiple times (it was a Purify Arena deck), such that I have a nice +10 counter when winning the game.
Tl;dr: Purify cast against player doesn't get reflected, Purify cast against opponent gets reflected. (See post below.)
I don't know how it's intended to work but I suspect that this inconsistency could cause severe desynchs in PvP. I expect Purify to work similar to Holy Light when it comes to these shields as it's a healing spell. If I remember correctly, Holy Light doesn't get reflected because only damage-dealing effects do.