There are also more subtle things like decks having enough instant-speed removal to sometimes encourage creatures to attack elsewhere, including several enchantments that sit in play and can kill at instant speed
Now, Hatred came out at the same time as a few powerful 1-drops like Sarcomancy and Carnophage, as well as fast-mana with the reprinted-and-still-legal Dark Ritual or the new Culling the Weak
Now, like I said above, the nature of your deck is such that you dont have to have your graveyard hate cards be super-hard in the abstract, but if you bring them in against the mirror, they have to do something to justify the cost
Gamble is another tutor option, but it has a rather risky downside of randomly discarding a card from your hand, including potentially the card you search for
The cost reduction ability reduces only the generic mana in The Great Henge's cost
Players will get (usually) three randomly selected 15-card "packs" taken from the cube