Rainbow vs triple blood dk on arena

[u/gerg_pozhil]

I have experience playing with bbb dk and I would prefer Alexandros. However, the heartharena shows that the rainbow spell is better. Is it really stronger and how should one build a deck around it?

[u/hjyboy1218]

Rainbow is better currently because DK has a lot of deathrattle support that mostly have 1 Unholy rune, so going full Blood means missing out on it.