Is Gravi-Crush and Magna-Slash Dragon good in a Crystal Beast Deck?

Question

Gravi-Crush Dragon

Level 6

[Dragon/Effect]

You can Send 1 face-up Continuous Spell Card you control to the Graveyard to destroy 1 monster your opponent controls.

Magna-Slash Dragon

Level 6

[Dragon/Effect]

You can send 1 face-up Continuous Spell Card you control to the Graveyard to destroy 1 Spell or Trap Card your opponent controls.

Answer 1

Yes

Answer 2

Yes they are both good in a crystal beast deck as long as you have ways to get back your crystal beast monsters from the graveyard.

Answer 3

Definitely, every Crystal Beast Deck should have them.

Answer 4

i heard only if you have rainbow dragon ready to summon then it can come out onto less traps.