During your Standby Phase, if this card is in your Graveyard and you do not control a "Treeborn Frog": You can Special Summon this card. You must control no Spell/Trap Cards to activate and to resolve this effect.
To answer people's question on why it can be summoned multiple times: when a card leaves and returns somewhere, it's treated as a new card. See for example: use a "once per turn"-effect, flip it face-down and up or destroy and revive it, and you can use the effect again. Same with Treeborn Frog: it left and returned to the Graveyard, so its "once per turn" has been reset, allowing it to be used again
Guess I should also explain why it now says "once per turn" when it seems unnecessary. It's for specific cases. For example: when Light and Darkness Dragon is on the field, you can activate Treeborn Frog, Dragon negates it, and then because of "once per turn" you can't activate it again to drop Dragon's ATK and DEF even further, since Frog in this case didn't leave the Graveyard.
Apparently it says
once per turn ingame (and in the yugioh wikia), but this site has left the once per turn part out of the card text.
Okay is this a new glitch or hack in ranked pvp?
I am at Legend rank. In my turn I destroyed this face down Treeborn Frog. Okay it was his turn he special summons it from graveyard, everything is fine so far. Then he used E-con and tribute his Treeborn frog to take over my monster, AND his treeborn frog effects activated again and came back to the field, so he eventually used my monster and the frog to tribute summon a 7 star but WTH it was not standby phrase and it happened twice that turn?