Ashes

Alpha's healing/barriers aren't amazing and he's mainly used for his buff that reduces damage by 25% from attacks that target 4 or more companions. This is very useful in cube (with 8 companion teams) and also in rift stages with the penetrating archers. 
Moreover, he buffs ally PATK/DEF by 10% and debuffs enemy PATK/DEF by 10%. 
Finally, his main skill casts a 4 second buff that gives the lowest hp target 30% HP reflect.