The cost-reduction ability of Lumbering Megasloth doesn't change its mana cost or mana value, only the total cost you pay. Specifically, the mana value of Lumbering Megasloth is always 12.
08-03-2024
wotc
Once you announce that you're casting Lumbering Megasloth, no player may take actions until you're done casting it. Notably, opponents can't remove counters from players or permanents to try to change Lumbering Megasloth's total cost.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.