It costs a lot of mana, though lets you destroy any permanent for no downside, which in certain decks can come up
A good example of this is that it's appropriate to side out your two copies of Honest when you're up against Macro Stun as they wont do you much good there, as Macro Cosmos, Dimensional Fissure, & Banisher of the Radiance render them useless
These two abilities actually work really well together, as the mana ability will give you the necessary resources to play the three cards you just exiled off the top of your library
You can do this multiple times each turn, so if you've got a way to draw cards you could set yourself up to build a decent storm count

Sort Card Type Hoppip #83Common $10.61 Hoppip #61Common $0.50 Hoppip #55Common $0.64 Hoppip #112Common $1.20 Hoppip #57Common $0.51 Hoppip #90Common $0.31 Hoppip #67Common $0.49 Hoppip #1Common $0.34 Hoppip #3Common $0.17 Hoppip #2Common $0.04 Hoppip #1Common $0.18 Hoppip #96Shiny Rare $4.00 Hoppip #1Common $0.12 Hoppip #1Common $0.20 Hoppip #4None $0.45 Hoppip #3Common $0.94 Hoppip - 005/190 #5None $0.10 Hoppip - 005/190 (Mirror Holofoil) #5None $0.81 Hoppip - 008/095 #8Common $0.88 Hoppip - 009/095 #9Common $0.62 Hoppip - 195/190 #195Shiny Rare $1.56 Hoppip (11) #11Common $0.20 Hoppip (12) #12Common $0.22 Hoppip (67) - 2010 (Yuka Furusawa) #67Common $1.86 Hoppip (90) - 2010 (Yuka Furusawa) #90Common $2.29 Hoppip (Mirror Holofoil) #4None $2.75 Hoppip #83Common $10.61 Hoppip #96Shiny Rare $4.00 Hoppip (Mirror Holofoil) #4None $2.75 Hoppip (90) - 2010 (Yuka Furusawa) #90Common $2.29 Hoppip (67) - 2010 (Yuka Furusawa) #67Common $1.86 Hoppip - 195/190 #195Shiny Rare $1.56 Hoppip #112Common $1.20 Hoppip #3Common $0.94 Hoppip - 008/095 #8Common $0.88 Hoppip - 005/190 (Mirror Holofoil) #5None $0.81
