Kreatur — Elf, Druide
2 / 2

: Bis zum Ende des Zuges wird ein Wald deiner Wahl zusätzlich zu seinen anderen Typen zu einer X/X Baumhirtenkreatur, wobei X gleich der Anzahl der Elfen ist, die du kontrollierst.
The value of X is determined when the ability resolves. It won’t change later, even if the number of Elves you control changes.
If you control no Elves when the ability resolves, the Forest will become a 0/0 creature and be put into the graveyard. However, since Elvish Branchbender is itself an Elf, the Forest will usually be at least a 1/1.
A noncreature permanent that turns into a creature can attack, and its
abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn’t matter how long the permanent has been a creature.