If you are really desperate to make the deck cheaper, you could probably trim a copy of Verazol, the Split Current and a couple of Coralhelm Chroniclers for another kicker card (whatever you do, don't cut Throne of Makindithe deck needs it to function), although I wouldn't recommend it
Before I begin with these examples, I want to note that mutate mutated a lot through both vision design and set design
Explorer's Guidance allows players to see the top six cards of their deck and put two of them in their hand while discarding the rest of the cards that were not added
If you decide that you want to take it a tad more seriously, you can pre-prepare your own 'decks' with the basic lands of your choice
ST06-015 Great Eruption While many other cards reduce cost in a way similar to this card, this is the only card that can reduce cost without consuming any cards in the players hand or imposing any conditions, making it powerful in every stage of the game