Deflecting Palm doesn't actually redirect damage, as many players commonly say it does. Since it prevents damage then deals damage of its own, lifelink won't matter for the creature whose damage was prevented.
Deflecting Palm prevents damage, then it deals damage (not quite the same as redirection!). This means there are two chances for replacement effects to apply to that damage. Read up on the details here!
Deflecting Palm can pretty easily cause a game to become a draw by preventing and dealing some part of combat damage from multiple attacking creatures.