James Wake could not possibly imagine what was hidden in the lake. He was also quite offended someone had taken one of his belongings. But it had come to a point where he did not care. He also knew that he could not swim, not with his false arm so heavy. If used alchemy on it now, it would be a little bit too obvious. James whipped his wand and mumbled the Bubble-head charm. He then thrust the wand back into his robe, taking in one assuring breath of air. He hated relying on magic. James dove straight into the depths of the lake. Trying to keep his body aligned as his arm pulled his body to the sandy floor, James felt it was safe to use Alchemy properly. Clapping his hands and running his real hand over the forearm of his Alchemic arm, he produced a weighted belt. Nothing out of the ordinary, and the amount of mass present in the arm was not significantly decreased. James then rolled up his sleeves, and stuffed excess material from his robe into his pants- nothing that could impair movement better than a wall of water.
He started in the direction of the lake's center. There was forest of thick weed in the way, so James took his wand out, testing its speed against the water. It was significantly slower. He would have cursed, but at least he had something that could make up for it. He had the Alchemic Arm. He took a sharp breath in and entered the forest of seaweed.
But the time he got to the center of the seaweed forest, he could hear the clacking noises and snarls of the Grindylows. Perfect, was the first word that ran through his mind. His predictions were still holding strong. Relashio! he shouted into his pocket of air as he pointed his wand at the closest. It took the hit and swam away, jabbering in its little language. Good news for James. The Grindylows now knew he meant business. His eyes scanned the weed for more of the offending little creatures, but he started moving, allowing his wand arm to droop just a bit. Terrible mistake. The Grindylows attacked him, surrounding him like and orb of snapping, red monsters. James felt them bite, cut and snap at him, but James had a contingency plan. He clapped his hands and perform some last-ditch Alchemy on his false arm. From the, a face emerged, as if it had been petrified mid-screaming. Thick serpentine hairs branched out from the side of the arm. The Grindylows that approached the transforming arm, chattered as they rushed away. It was the face of Medusa, or a pretty convincing imitation. The Grindylows fanned away, avoiding the horrifying face, chattering in their language about something or the other. James took this moment to cast his Bubble head charm once more, to replenish his oxygen supply. He felt the sharp cuts of the 'lows, but he chose to ignore them for now. The lake was not composed of Salt water, but whatever bacteria infected the wounds could be easily dealt with later.
James took a moment to consider the implications of his last thought, and set about healing the cuts with quick cuts of Episky.
James trudged forward along the floor of the lake, and saw some fellow students fighting off the Merpeople. Understandable. From what he had read, they could be vicious when asked to. Normally, however, Merpeople could be quite reasonable. He transmutated his arm back to its normal self, its familiar weight now a burden. He recast the Bubble-head charm just to be safe.
The Merpeople were on him, with spears, snarls and songs of doom. James flicked his wand between the closes of the people, switching between Flippendo and Relashio. He had half a thought to use more brutal spells, but the people down here probably took a beat each Hogwarts sent its students down. He approached his floating box, and tugged at the chain, transfiguring one more jabbing spear into an squirming eel. The box contained a little trinket of little sentimental worth to James, much to his disappointment. He fingered it, wondering what the Proffessor had thought it meant to him, before fending off three more merman, and casting Ascendio! to propel his heavy form to the surface. It only pulled him so far. James swore, transmutating the belt back into his arm, and then transmutating the arm into a lighter form of aluminum. He tried the spell again, this time break the surface, silver trinket in aluminum hand. He swam to the shore, despite the impeding arm, and flopped onto the shore. He quickly tugged his sleeve back down to hid the aluminum, and showed the professor his silver trinket. "Happy?" he panted.