That's your problem. You see the thing is you should do a focus build. Focus on either archer, warrior or mage. That is your best bet for the game.
Focus your stat points into vitality and your one major stat for whatever build your going through. So if your a mage, Intelligence and Vitality with some points into spirit to increase your overall mana pool. Let your armor take care of the rest for attack resistances to ranged and melee.
If doing archer, go Dexterity and vitality.
Warrior, Vitality and strength.
That's what you need to do. you also need to buy lots of powerful heal potions and spam those like crazy. For abilities you should put at least 5 points into regenerate, a warrior skill no matter what build you have. It helps your health regenerate while in battle.
There is no special battle strategy for taking out Ygerna end game battle.
