Well since people are plugging Story Hours, here is a shameless plug for mine

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BTW, I agree with AuraSeer. IMC, powerful celestials do not appreciate being summoned any more than powerful demons or devils. On the other hand though, if you are of like alignment they would probably let you off with a warning.
Situation #1 -- LG Cleric uses Greater Planar Ally to call a Solar
Everyone stood warily around Joachim as he completed the words to the incantation. The Inquisitor had demanded that Justice Hythal clear the entire temple. He had never before requested so much from Tyr and he wanted no interference.
As the spell was completed, the entire room was suffused with a radiant golden glow and seemingly out of nowhere appeared a being that was law and justice personified.
With gleaming white wings, eyes that that were like pools of molten gold, the nine-foot tall creature addressed the Inquisitor, "Joachim Dethick, High Inquisitor of Tyr! The lord of justice bade me to parlay with you. What is it you require?"
As quickly as he could, Joachim explained the situation with Irae T'ssaren, trying to describe the Great Revenance and the threat to the Dales.
The mighty Solar's expression did not change when Joachim finished. "Inquisitor, I am the mightiest servant of Lord Tyr. I am tasked with the enforcement of justice throughout the planes. Yet, you have the gall to ask me to act as your shield man in a regional conflict?"
"I am sorry if I offended you sir. However, the threat is not merely a regional one. If T'ssaren's plan is successful then the entire world of Toril may well feel the result. And this drow is indeed a powerful enemy, worthy of your attention. Some suggest that she is the a Chosen of Kiaransalee."
The Solar listened carefully, but was not convinced, "Tyr has gifted you with mighty powers. On this material plane, you are among his most respected and influential clerics. I am certain that destroying this drow with your current companions will not be an insurmountable task."
Seeing that he could not press further, Joachim nodded, "I understand sir. I am very sorry for wasting your time. Farewell."
"Yet, I am not without concern for your plight Inquisitor. Though I do not deem it necessary to intervene directly in your affairs, I will grant you a boon."
Joachim thought for a moment, "Sir, our previous incursion into T'ssaren's stronghold have most assuredly put the place on high alert. It would be very difficult for us to defeat all her undead minions again. By the time we reached the drow herself, we would be ripe for killing. I humbly request that you provide us with transport into the heart of her stronghold."
"I will agree to such terms. However, I also require something in return," the golden eyes slowly looked over the other party members as if penetratrating their very souls. The celestial finally stopped when he reached Noir, "Inquisitor, I see that the holy champion in your group has a sword of great evil. It was forged in the Lower Planes and constructed to bring about chaos and strife. It is not appropriate for individuals such as yourselves to be using it. Give it to me and I will dispose of it properly."
Noir was taken aback for a moment. With the vorpal greatsword, she was better able to serve the cause of law and good by destroying many evil opponents. However, her foremost concern was the restoration of her homeland so she reluctantly handed the weapon to the Solar.
Situation #2 -- NE Sorcerer uses Gate to call a Solar
The Solar stared at Entropy with a gaze of pure hatred, “You will pay for summoning me mortal! Even the greatest of Heaven’s champions may not call on me when they are in peril. Yet you have the gall to compel me to fight your battles? Your arrogance will not go unpunished!!”
“Wish her back.”
“What!?”
“You heard me Solar, wish the Cathezar back!”
Seeing that he would have to back up his words with actions later, the Solar complied. Attuning himself to the Weave, he tried to grasp the form of the Cathezar and wrench her back to his location. Though the Solar’s spell was mighty, the demon’s resistance to magic was mightier still and nothing happened.
“It cannot be done.”
“Unfortunate. Then your service to me is concluded.”
The celestial’s eyes narrowed, his visage becoming one of pure anger. The sight would send most mortals running for their lives. “Remember my words sorcerer. You will pay.”