Evenglare
Adventurer
For what it's worth. The rule reads that the minimum hitpoints you REGAIN from the roll is 2xCon. If it said "The minimum number rolled is 2xCon, the I'd agree with those that say you get 15, but it doesn't say that at all. So you roll as normal 1d6+5 to see how much HP you gain. If that number is less than 2x Con (10 in this case) then instead of the roll you gain 10. The feat doesn't seem that terribly worded or complicated to me.