According to players in community discussions, you should focus on "solo missions, grinding quests, also there are events that pop up every 1-2 weeks with semi consistency." Completing these objectives is one of the most reliable ways to earn Pack Hourglasses, in-game currency, and even more free packs
The pull rates will likely be the same, however
Airknight Parshath Curse of Vampire D.D
They are unlikely to be spawned by the Agenda advancing as their evade is so low, but the Serpents Ire is much more likely to bring them than anyone else
Nylea, God of the Hunt Nylea, God of the Hunt is solid combat support for any green creature deck
Ice type coverage helps keep most Dragon types in check as their second types often are also weak to Ice