@ Shruthi, belief is something which differs from person to person and family to family. In my family, we are not allowed to keep the Geethopadesh photograph or the painting as they feel that will bring in fights between the family (brothers) though we are allowed to keep Bhagavathgeetha copy. We are not allowed to keep the photo of Kodandarama (Ram with Bow) but are allowed to keep Sriram's photo with Sita, Lakshman & hanuman for a simple reason, if we have Kodandarama photo, the head of the family will have to be on toes to face enemies or danger will be hovering over the head.
In case of Ramayan, Sam& Dana were used more and only in the end danda was used. But where as in case of MB, Bhedha was most used which resulted in Danda.
Even though Ram killed Vali to help Sugreeva, he was not fully convinced and he felt bad when Vali questioned him about the same. but Krishna never felt bad to create rift between a son and mother or between friends or between brothers. He didn't hesitate to use Kunti to save Arjun by revealing the birth truth of Karna to her and his open meeting with Karna alone created rift between Kaurava Sena.
When he realized Abhimanyu learnt more than required while he was narrating the story to Subhadhra ( about chakravyuha), he stopped narrating the story and ensured he entered the Chakravyuha by taking away Arjun from the war field so that he is not there to save his son.
When Gandhari wanted to make her son (Duryodhan's) body unbreakable (vajrakaya), he ensured Duri wear a shorts so that that covered portion of his body will left vulnerable.
The list goes on and on. So if Krishna wanted, he could have saved Abhimanyu, if he wanted to save Karna, he could have done.
The last thing about Krishna's conspiracy was in killing Bheema's second son "urdhwabahu" (Ghatothgaja's brother). He tricks him that if his father's (Pandava's) have to win the battle, he had to find an animal which as hair grown upward and his father has to sacrifice that in the battle field by end of the day. The poor guy wanders all through the jungle and exhausted will finally stop near a pond to drink some water where he sees his image and realize that Krishna meant him to be sacrificed. So he ties himself in a sack and place himself near the sacrifice place and Bhima without realizing it was his son will hit the sack so hard that the head separates from the body and places itself on the lamp post. Even then Krishna takes a promise from him that he can watch the war silently and the moment he opens his mouth, the head will break into pieces.
And about Prahlad, he was not aware that the lord whom he pray for will be furious enough to kill his father. Prahlad never thought his father was evil and has to end, all he wanted to say was that Lord Vishnu is great and is present everywhere. he was shocked beyond imagination. He never planned & plotted the muhurath for his father's death
Sorry if I have unintentionally hurt anyone's feelings (as I know many of you are devotees of Krishna and believe in him more).