Because Thoros's only mission was to protect domain of titans, he did not fought in war against gods. Therefore, he stayed there to protect the gate until the leaders be free one day and return home.
Chronos knew a true titan left in domain of titans. Thus, he went to kill him, and once he got in front of the gate, and before he even recognise anything, Thoros attacked him. He was so fast compared to his massive size and he almost crushed him. Chronos immediately attacked back, but barely did damage, and the battle continued. Later on, when the battle took too long, Chronos realised that he has no chance to take him down, so he decided to steal an amount of blood with less consequences, and indeed, he managed to do it using his magical powers. Thoros noticed and knew that Chronos was thinking about. In the moment Chronos was about to leave, Thoros's first word was " Do not do it". Likely, Chronos thought that he meant to stop him from going, but in fact he warned him to not destroy the purple stone.
In Chronos's Castle....
Trophos : care master, you look tired.
Chronos : do not worry, I am good, ooof!!!!!. He was fucking stronger then I expected! I should have just got the blood and get the fuck out ( laughed tiredly).
Trophos : shall we start now?
Chronos : yes, let us do this.
Chronos poured the blood of the titan on the stone and requested for the infinite power, and unexpectedly, the same purple light emanated the same way it did with Agamemnon and absorbed Chronos. After that, the purple got activated, which finally allowed titans to get red of the lighting chains of Adonis because the planets and stars flowed again, and titans got their freedom. Trophos got frozen in his place, because he felt so terrified and disappointed of what happened.
( a dialogue....)
Trophos : ( while sitting on his knees crying) forgive me your majesty, I was responsible for all of this, it was my fault not predicting what could happen.
Chronos : hello old man, do you know where the bathroom is? I really can't holding longer then this!
Trophos : ( mumbling in his talk), but, but, you supposed to be dead!
Chronos : stop underestimating, did you forgot who I am? I can teleport through dimensions you idiot! And by the way, I Brought a guest, say welcome.
Trophos : ( his knees stopped responding) holy Chronos!!!
Without Chronos's dimension gate, he would have been stuck in the purple stone for ever. Apparently, Agamemnon was still alive inside the dimension of the stone, and before the gate was about to be closed, " jump in my gate, you will not get another chance " Chronos said. Agamemnon instantly leaped in the port and got saved. Out of a lot of confusion, and after Trophos got deep in his studies. He discovered that the purple stone has no ability to give power, and all what was written in the holy book was a conspiracy from Vasilïas ( Creator of Titans) and Vassïlisa ( Creator of gods).