Dragon Emblem Tips?

I want to build a dragon emblem team,
So far, these are the units I've got;
H!Myrrh (+HP -RES)
Likely going with a budget build cuz no DC yet.

Myrrh o.g (+DEF -SPD)
Probably the first person I give DC to cuz perfect IV's

L!Tiki (+ATK -SPD)
So far has her base kit but open to suggestions.

Please comment if you know of a good dragon that can fill the void in the fourth slot, thanks!
Also, I am an F2P player who is completely incapable of spending money, so nothing too insane plz.