Here are a few I like
A push towards slow grindy Blue heavy decks is something I think you wanted for your cube. This is pretty good at that. You don't have Bouncelands to abuse it, but you do have
Cryptic Command up to you if that's unfair or cool.
Surprised this isn't in your list, seeing how pushed the GY theme is in Green. It's more often than not a creature land, but sometimes it can be a second
Mindslaver activation from your mana base.
Sweet land for either landfall decks (KoTR,
Elvish Reclaimer,
Harrow and friends) or for
Wildfire,
Goblin Trenches or
Bound by Moonsilver. Doesn't go into many decks, but low opportunity cost makes it fine.
Same idea as above!