Book about a wizard being turned into a woman by magic itself (magic is a female being)

Question

There was a tower in it as well. Where a wizard tried to protect his tower with crabs magical modified with other animals. And people being able to go into trees.

What is the book series called? I read it 10 years ago, I think.

Answer 1

The title of your question makes me think of the Forgotten Realms novel Elminster: The Making of a Mage (1994) by Ed Greenwood.

The titular character is mentored by (an avatar of) Mystra, the goddess of magic, who at one point transforms him into a woman to help him learn stuff.

Elminster bent forward to take it up. There was an unfamiliar swaying sensation at his chest as he knelt. Frowning, he looked down and saw the breasts and the smooth curves of a maid. Elminster stared down at himself in astonishment, and ran a wondering hand over his body. It was solid and real... he looked wildly around, but he was alone. Mystra had turned him into a woman!

[...]

A flame was burning under the water, a flame with nothing to feed on! A flame that was rising, and becoming golden... Mystra!

He reached out an eager hand to touch the flame as it broke the surface, never thinking that it might destroy him until it was too late and his slim fingers were already feeling-coolness! A voice seemed to speak in his head. "Elminster becomes Elmara to see the world through the eyes of a woman. Learn how magic is a part of all things and a living force in itself, and pray to me by kindling flame. You will find a teacher in this forest." The flame faded and Elminster shivered. He knew that voice.

The elves can shape themselves into trees (into other forms as well, Baerithryn (Braer) shapes a wolf at one point to go hunting, but they shape trees when they want to wait, or be inconspicuous:

"Braer," she said into the darkness. Please... come back!"

A tree nearby wavered and bowed-and then stepped forward. It was Baerithryn, looking sad. "Forgive me, Elmara?"

and

Braer sighed and continued, "You, and others like you, we can aid in your own battles against them... and we will. So long as you respect the land and live with it, our ways lie together, and our battles shall, too. When you need aid against the magelords and call to us, we shall come. This we swear."

A moment later, half a dozen trees around them shifted and stepped forward, and his words were echoed by a fierce chorus. "This we swear."

Elmara stared around at all the solemn elven eyes, swallowed, and bowed her head. "And I, in turn, swear not to work against thee or the land. Show me how to do this, please."

The towers are occupied by the Magelords, the main antagonists of the book, and the magical crab modification bit is an experiment by one of the magelords:

In a dark chamber high in that tower, glowing water splashed. Its reflections danced across the intent face of Undarl Dragonrider, mage royal of Athalantar.

The griffons struggled in the water, fighting his spells. If he could ever get them to mate in this vat of enspelled giant crab fluids, a few simple spells afterward should give him what he was after. The offspring would be flying armor-plated killers ruled by his will... and he'd have taken his first step beyond what the most powerful sorcerers of his family had ever achieved.

The gods above knew he was growing weary of waiting, though. Undarl sighed and sat back in his chair, listening to the water surge up over the edge of the vat, the overflow slapping against the wall beyond.