From episode 4, "Betrayal," onwards, mentioned by name from episode 5, "Victory," on. The power to control nature and the elements. Ecomancers, also known as "ecomance healers," are the people with the ability of ecomancy. Teron uses the phrase "elemental touch" in reference to this power as well. Teron and Tula are both ecomancers, the former a supreme ecomancer, I believe, and the latter recognizing her power in "Andorus," while on the island of Andorus.
Ecomancers have the ability to make plants grow with supernatural speed, control wind speed and direction, make the ground crack, alter the direction of the water's current, spread flames, communicate with animals, and possibly send psychic image-messages. They also can sense impending feelings; Tula senses danger just before something bad happens, for example. On Andorus, homeland of the ecomancers, it was the ecomancers' job to keep the island healthy and guard it from the evil, nature-killing Blight. Teron, while imprisoned on the Maelstrom, was supposed to manipulate the sky and the sea so that the Maelstrom could sail clearly, and Tula snuck onto the ship to free him in order to bring him back to Andorus to save the decaying, dying island.
From episode 4, "Betrayal." A form of torture cheerfully suggested by Bloth's new brigmaster as an option for dealing with their new prisoners (who, unbeknownst to them, are Ren and Niddler). I'm assuming this is the same thing Joat tried to do to Ren and his crew in episode 20, "The Soul Stealer," by trying to feed them to a pit of dartha eels.
From episode 20, "The Soul Stealer." Rods that have the heads of some species of electric eel at their heads, and these eel heads still retain their electric charge. We see them predominantly used by Bloth's crew; these rods are used to incapacitate people/creatures, and had been used in previous episodes, like in episode 16, "The Dagron Master," when Bloth's pirates use them to keep Ren in his dagron form under control.
Eighth Treasure of Rule
From episode 21, "The Living Treasure." It's special in several ways. It's the last Treasure uncovered in the series, in the final episode. It gave the crew the hardest time to find--it took them nine episodes and many months to actually find it, and then did so entirely on accident. The most interesting trait about this Treasure is that it's alive. It's a small, light-blue, furry creature called the margar by the Delpha warriors. It has a "growing" touch, similar to that of Tula's--except this creature can make plants grow faster, and help animals heal more quickly. It made Niddler's feathers grow back in the blink of an eye when they fell out after he hurt himself, it made a minga-melon grow, and it restored plant and floral life to Octopon.
Eighty-five pieces of gold
From episode 5, "Victory." The price that Bloth will pay Tula for the Compass and First Treasure.
From episode 6, "Andorus." Teron's phrase to Tula regarding her ecomantic powers ("You have the elemental touch--the power of an ecomancer!"). An ecomancer can control nature, but s/he can also control the natural elements--air, water, earth, fire, and so forth.