Like most questions in Magic , your first instinct is probably to answer the above situation with "It depends." But as a default state, what would you do
Meanwhile, the Rank 7 monsters offer extension, protection and recursion for used "Dragon Rulers"
Now, you probably need this to trigger twice before you feel okay with it, but the fact it gives you one of those triggers the turn you play it helps make up for that, as this will usually do something to the board right away, and its a value engine after that Lots of decks want to run as many permanents as possible because of Descend, and the Boulder gives you a removal spell that is still a permanent
[F][C] Seismic Toss: 150 damage
It taps for one Blue mana, but deals one damage to you, which isn't great, but it's mostly used for its Threshold ability: Once you have Threshold, you can sacrifice it to draw and then discard three cards