Toward the end of the Kurukshetra war, Ashwathama uses the Brahmastra on the unborn child of Abhimanyu to end the Pandava dynasty. Before that he killed all the Pandavas' children in the dead of the night in stealth, breaking all the rules of war that Bhishma had framed.
His rationale for this is that the Pandava's themselves had broken several rules and they killed all the Kaurava heroes by cheating. Which is true. Drona was disarmed by a lie and killed when he had cast away his bow and arrows and was grieving for his son. Karna was unlawfully killed. So why not the upapandava's ? And why not the unborn baby ?
Krishna revives the baby and curses Aswathama to eternal pain from a festering wound on his forehead. Why ? Why ? Why eternity ?Is'nt God supposed to be merciful and ever-loving. What kind of a curse is this ? Eternity ... ETERNITY !!!
Why did he refuse to not use wepons himself and then use all kinds of trechery and devious means to kill the Kaurava warriors ? And why was Aswathama cursed so ? Why is there a Brahmastra that can destroy the universe and why is he cursed for using it ?
Why is there a right and wrong and a complex dharma defining it if at the end of it whatever 'God' does is right and most other stuff is wrong ?