5 mana for a 10/10 is an incredible deal, and easy to accomplish in a mono-green deck
(Okay, technically I have a third option to do some of each.) Using -1/-1 counters as a cost essentially lets you swap power and toughness between creatures
For example, the 2023 Scarlet & Violet sets feature reverse holo cards of this nature
My biggest miss in the list of best cards from Modern Horizons 3 was Phelia, Exuberant Shepherd, which turns out to be pretty nice in an aggro shell, and this card may very well go in that deck
For example, you may play a land only during your main phase while the stack is empty
However, one of the targets can be the creature you intend to sacrifice to pay Ruthless Disposals cost