Boseiju, Who Endures A dangerous tree Boseiju, Who Endures is an ancient tree that protects the world of Kamigawa and, being the embodiment of Green on this plane, comes with a fairly powerful ability
Moreover, The Spear of LeonidasThe Spear of Leonidas (which is fast becoming my favorite UB card
Sacrifice decks often tend to run ways to retrieve cards from their graveyard, so you can keep reusing this land to get excellent mana fixing while empowering your board
As long as you can make a land drop and put Chasm into play, it leaves you mana-neutral
The first time you copy a Sword of Hearth and Home with this is going to feel amazing, and thats only one of the many interesting things you can do with it
In addition to being a great mana rock and callback to Coalition Relic, this card is simply waiting to be used as an infinite mana outlet