There is also another aspect of these changes.
When there are epics, rares are less desirable than before, what means the economics will be affected too.
And because this is the only feature that gives to the trade cross-realm relationships, it needs to be carefully observed.
I can imagine that with a cascade of training stones, pet-related sections of Auction Houses will be paralysed or unpredictable for several months. Then blue pet prices will drop to the nether and the purple pets will take their place.
If my main suggestion was implemented as the
only source of purple pets for a patch or two, people would think twice before putting a purple pet on AH, so the blues' value would drop slower to the day the restriction is lifted.
Including that all, the mentioned WoD-like RNG factor (if it's a thing) would sadly add more grind to the pet farming.
To prevent this, I need to add that a chance to get an epic should be related to your progress as a tamer.
A cosmetic addition to the epic pets? Sure! I guess that a purple mist was just an example? It would not fit to all pets, especially with a Fel Petal applied (would make them gray instead). Maybe a special symbol above them?
EDIT: @Quintessence -- I guess that's all.
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