**1. Ravana's story** As defined in your question: > Here person A is **Yama** and person B is **Ravana**. As per [UTTARA KANDA of Ramayana][1]: Kaladanda (the rod of time) is weapon of Yama. This rod of time, immeasurable might and incapable of being resisted by natures, was created by Lord Bhrahma as having the power of compassing the death of all beings. If this alights on any one, he doth not live for a moment. But Ravana also got a boon from Lord Bhrahma and he was incapable of being slain by Nagas, Yakshas, Daityas, Danavas and the Devas. **How that situation got resolved** When Yama wanted to kill Ravana with his Kaladanda (the rod of time), the great father (Lord Bhrahma) manifesting himself and spoke unto Yama: > O mighty armed one, O thou of imeasurable prowess, this certainly must not be: Thou shouldst not with thy rod slay the Rakshasa (Ravana); for, O the foremost of Devas, I have conferred a boon on him; thou shouldst not render false the words that I have uttered. Verily he, that, whether a god or a human being, who falsify my words, shall render this triune universe waste. There is no doubt about this. Whether on this weapon allighting, the ten necked (Ravana) does not die, or if he dies, either way falsehood is the consequence. If thou have any care for these worlds do thou establish my truth. Thus addressed, Yama then answered, I restrain this rod. Thou art our Lord. But as I restrain not slay this one who hath obtained a boon, what then shall I do now in the battlefield? Therefore shall I disappear from the sight of this Rakshasa (Ravana). Having said this, even thus did he vanish with his car and horses. **2. Daksha's story** As defined in your question: > Here person A is **Veerbhdra** and person B is **Daksha**. *As per the "Sati Khand" of Part 2 (RUDRA SAMHITA) of Shiva Purana* > After Sati jumped into the fire during Daksha Yajna. Lord Shiva gave a **curse** to Daksha that he must be killed and sent Veerbhadra to kill him. From the fear of Veerbhadra, Daksha prayed Lord Vishnu and got a **boon** that his life will be saved by Lord Vishnu. Lord Vishnu decided to fight on the side of Daksha. But Veerbhadra pulled Daksha out and severed his head. But Lord Vishnu gave Daksha a boon that his life will be saved then how he can be killed. But Lord Shiva gave him a curse that he will be killed so how his life can be saved. Hence, a clash between curse and boon (i.e Deadlock). **How that situation got resolved** > Lord Vishnu asked Lord Shiva to give Daksha's life back. Daksha was absolved by Lord Shiva and the head of a male goat was fixed on the decapitated body of Daksha and gave his life back. **Note:** Narada, who was listening to the divine tales of Shiva with rapt attention, was very curious to know about the reasons why Lord Vishnu attended a yagya where Shiva was not invited and why did he fight a battle against Veerbhadra. Lord Brahma told him that all this happened due to the curse of Sage Dadhichi. The story of the curse is also given in the "Sati Khand" of Part 2 (RUDRA SAMHITA) of Shiva Purana. As most of the incidents are repetitive hence other Purana might depict the story from some other Kalpa and may not mention that Lord Vishnu fought from Daksha's side. **3. Drona's story** As defined in your question: > Here person A is **Dhrishtadyumna** and person B is **Dronacharya**. As per [this chapter][2] of Mahabharata > Dronacharya got all celestial weapons in a **boon** from Lord Parshurama. So it was not possible for anyone to kill Dronacharya in a straight forward battle. On the other hand, as per [this chapter][3] of Mahabharata > After Drupada's yajna, the voice of some invisible spirit in the skies said, 'This prince (Dhrishtadyumna) has been born for the destruction of Drona'. But how Dhrishtadyumna can kill Dronacharya who is so powerful after Lord Parshurama's boon. Hence, a clash between two boons (i.e Deadlock). **How that situation got resolved** > This is already discussed in [this question][4]. **4. Soma's story** As per the chapter *'THE ORIGIN OF **SOMNATH**' of Shiva Purana - Part 4 (KOTI RUDRA SAMHITA)* > Chandra or Soma (the **Moon** god) had many wives, one of whom was Rohini. Soma loved Rohini very much, which made the rest of his wives very jealous and angry. They went to their father - Daksha and complained about Soma's behaviour. Daksha went to Soma and advised him to give proper attention to all of his wives. But it did not have any effect on him and he continued giving special treatment to Rohini. When Daksha came to know about this, he **cursed** Soma to become weak and devoid of radiance. Then, Soma went to Prabhas area and chanted Mahamrityunjaya mantra. Lord Shiva appeared before him and asked him to demand anything he wished (**boon**). Soma requested lord Shiva to liberate him from the curse given by Daksha. Hence, a clash between curse and boon (i.e Deadlock). **How that situation got resolved** > Lord Shiva told Soma (the Moon god) that the words of Daksha can never became untrue. However he blessed Soma by saying that he would wane during the dark lunar phase (*krishna paksha*) due to the curse, but wax during the bright lunar phase (*shukla paksha*) due to his (Shiva's) blessings (boon). **5. Banasura's story** > Described in [Śrīmad-Bhāgavatam (Bhāgavata Purāṇa) 10.63][5] **6. King of Kashi's story** > This story might not have scriptural basis; it may just be folklore. It is discussed [here][6]. There may be many more instances of such Deadlocks: As per few stories, **Bhishma** had a **boon** that he can choose the time of his death and **Shikhandi** (or Amba in previous birth) had a **boon** that he/she will be the cause of Bhishma' death. So, this was also the case of Deadlock. [War between Danavas (from Rasatala) and Ravana][7] also resulted in Deadlock which was resolved by Lord Bhrahma himself. [1]: http://ancientvoice.wikidot.com/src-vrm:ram7-22 [2]: http://www.sacred-texts.com/hin/m01/m01169.htm [3]: http://www.sacred-texts.com/hin/m01/m01170.htm [4]: https://hinduism.stackexchange.com/questions/19005/how-dronacharya-royal-guru-died-in-kurukshetra/19008#19008 [5]: https://www.vedabase.com/en/sb/10/63 [6]: https://hinduism.stackexchange.com/questions/834/why-did-hanuman-fight-with-lord-rama [7]: http://ancientvoice.wikidot.com/src-vrm:ram7-23