Not only can you look at the top card anytime, but you can also play historic spells and lands from thereartifacts, legends, and sagas are fair game
You can add madness cards to your deck like Big Game Hunter or From Under the Floorboards
Whether you're using enchantments for removal or as a buff to your battlefield, the only way they'll end up in the graveyard is if your opponent destroys them
However, removing a counter from a saga with something like Glissa Sunslayer sets it up to trigger the same chapter during your next turn, which can help you loop certain saga abilities
In fact, thinking about it more Im fairly confident that more different decklists will contain at least one Deicide in the 75 than any other card in the set, so I suppose its clear that Im not giving full credit for sideboard inclusion
If at least one Zombie card is milled this way, each opponent loses 2 life and you gain 2 life