J-Bo89, The best part is you can equip the single icon bomb spell while you are setting your mage up before starting the game. This is very handy to have when you head into the wilds.
I avoid friendly fire damage simply because I usually play on easy unless I'm experimenting with new ideas then its casual. Personally I see no need to make the game ridiculously harder for me since I don't have full use of my right hand. I get flack from my son and Grandson because I don't use hard or nightmare but,to each their own style of game play is fine by me.
Another good spell to have later in the game is "animate dead".. This allows you to raise enemy dead so they will fight on your side.This spell is next to the three icon walking bomb. Comes in handy during the Battle of Demerim. Other spells to have is group heal, fireball, blizzard and tempest.. Serious damage is done when I use these spells so, I place my group on hold ground. If I'm using my normal three rogues then Morrigan is equipped with those spells.
Oh yes..I forgot the "knock back" spell.. This protects your mage from attack by relatedly knocking the enemy down before they can attack your mage. Very handy.
If you are interested there are other tutorials on you tube explaining the best setup for warrior and rogue.