This part of the card is rather unexciting but can still be useful if you are low on action
With four different character cards printed as of OP-04, he rivals the protagonist, Monkey D
So while some decks might struggle to produce a big payoff from an X spell, green strategies are often well suited to produce lots of mana in a short amount of time, allowing cards like Invasion of Ikoria to suddenly apply pressure with whatever creature is going to be the best solution to a given situation
Herd Heirloom Herd Heirloom is a great green artifact for creature-centric decks
Ideally, theyre going to help you get more value out of each card, make your side of the board a bit scarier, and maybe even win you the game on the spot
I think the few mana dorks you have are good and you're not running the more redundant ones like Elvish Mystic, etc