It took me forever to understand how iframes worked in Dark Souls. I had already bounced off the game once and had jumped back in a year or so later determined to figure out what everyone was talking about. I swear I ran that bridge area in Undead Burgh a hundred times figuring out the mechanics. If someone had just point blank told me as I started the game that there is a portion of your roll where you are completely invincible and that it doesn't matter where you are or the enemy attack hits during that part of the roll, it would have saved me a lot of streess and trial and error.