Unsure what your opponent means by "it doesn't activate, it misses the timing"? Confused why your opponent is saying "during damage calculation" before activating Kalut? Unsure why Catastor doesn't destroy face-down monsters but a FLIP monster's effect still activates after being shuffled back into the Deck by Ehren? We've been hard at work compiling a thorough "Rulings & Erratas" page complete with the most updated card texts that were available at the time of SJC - Edison 2010. Find hidden tech to up your game and innovate new strategies! Afterwards, head on over to the Battle Phase Breakdown for a detailed breakdown of the 7 timings of the Damage Step, and use this handy flowchart to make sure your effects are resolving on time!
"If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle." - Sun Tzu