literally nothing
It lets you return a creature from your graveyard to hand, then its void ability kicks in, giving it a +1/+1 counter
This triggering often wont do anything to your opponent or help you cast anything
(2024-06-07) Rampant Frogantua's second ability counts every player who has lost, no matter how the player lost the game: due to a state-based action (having 0 or less life, trying to draw a card from an empty library, having 10 or more poison counters), because of a spell or effect that states they lose the game, because your awesome might has left them with no choice other than concession, or for any other reason
[13] Remember the phases of the turn: Untap : Untap all of the lands, creatures, and permanents on your board
In exchange for entering tapped, you get a green/black land that can transform into a beefy 4/4 creature, with not-insignificant upsides, when needed