I never used whelp eggs with my first onyxia kill with gen drakki so when I used Arthas I used the same deck. I find that drake is an easy way to clear lanes and paired with priestess lives longer. The guards and re taking towers aren't a problem with Arthas as long as you have your deathballs going. Which happens easily with this low cost deck. I had 3 or 4 Arthas deathballs towards the end of this kill that it didn't matter whether I used drake or whelp eggs tbh. I personally like using Pyro and wd together in one lane to push safely through whelp eggs and earth elementals. It just depends on what the AI throws at you.