Yamato rubs his hands together as his excitment grows. He knows that he finally getting into the good stuff.
Remembering back to his training, Yamato remembers that yin chakra is related to fire and Yang chakra is related to water. In order to cultivate chakra a ninja would normally gather both yin and yang in various quantities and mix them to produce a desired result. Yamatos plan for this first attempt is to gather both yin and yang, but not mix them. He intends to redirect both of those energies towards his arms instead.
Yamato holds a peice of paper in each hand, close his eyes and visualizes the chakra coursing through his body. He gathers yin energy from his mind and directs it to his left hand, while he takes yang energy from his torso and sends it to his right hand. He concentrates hard and after a few moments pass...
(Xylon can give the verdict as to what happens)
Appears to me you can now activate at least two natures at the same time. Try nature transformation now, see if you could materialize water and fire at the same time
The chakra paper in Yamato's left hand burns to ash while the chakra paper in his right hand becomes water logged.
With the instruction from his sensei, Xylon, Yamato continues with his training by attempting to materialize fire chakra in his left hand and water in his right.
Before the attempt, Yamato remembers Naruto's wind training and creates as many shadow clones as he can muster while still leaving himself with an acceptable level of chakra. Two shadow clones appears and all 3 Yamato's get to work.
A Full day passes as Yamato and his brothers gradually come closer and closer to materialising fire in one hand and flames in the other. Work out and exhausted, Yamato lies down and releases his two clones to gather all the knowledge they have accumulated. After recovering from the mental exhaustion, Yamato channels fire chakra to his left hand and water to his right. A small flame sits above his left palm while a grapefruit sized orb of water floats above his right palm.