These cards are excellent in aggro decks as you rarely need to reach more than five mana (most winning aggro decks should end their curve at four mana, with Hellrider/Hero of Bladehold-type threats) so the ability to not draw dead on a land is a huge boon
One is colours, it is already in two and those are two of the weaker combo support colours for this style of deck
Once it's successfully cast, all nonbasic lands are destroyed
As for how all this will affect the game itself, Id say itll be pretty big stuff
Once this card is in the graveyard, you can trigger its effect by casting a creature that costs 7 or more mana, which is quite convenient
Today, were putting the spotlight on the Rainbow Rare, one of the more unique art variations in recent history