Maybe the longer we keep the same Wyvern alive in a single zone, the EXP bonus HP/Attack/Resistence can occur naturally? Or make gear that enahnces "Call Wyvern" with each piece acting like +250 EXP was gained when we Call Wyvern, the full set could give the full +1000 exp bonus parameters when we wear it while equipping Call Wyvern. Maybe a set effect for 5/5 DRG relic +2?