NPC Regenerations
You can find him in Rock City:

We can regenerate there:
1x Bonus KI = 5g
1xBonus HP = 5g
1x Power recover = 15 g
1x Injection power = 20 g
and he is needed too for mission with Rider Mastera, to avaialable kill Boss Dragon - need to bring him:
10x diamond
16x red crystals