(Example: Control and Might for warriors are not meant to be able to be activated at the same time)Activate one, and before it's done casting, activate the other. It should activate them both and you should get the affects of both. This works for all sustainable abilities that are not meant to be able to be activated simultaneously.
To do this glitch, you need to obtain the Makers Sigh potion and lots of it. Start by assigning your available abilities to your tactics menu. Once this is done, use the Makers Sigh potion. Using this potion will remove all your abilities. Now save and reload that save. Go into your ability menu and you will notice that the abilities you assigned to your tactics are already unlocked, but you still have all your unassigned ability points. You can either use the Makers Sigh potion again and save then reload, or assign your points to other abilities, put them in your tactics menu, and repeat the rest of the glitch for even more ability points. This glitch also allows you to unlock certain abilities in classes without having to go through the entire skill tree.
This can be done with Aveline or Warrior Hawke at any point in the game. All you have to do with either is to equip and then un-equip and then re-equip a shield. Your Armor number and percent continues to go up as you equip and un-equip. Do it as many times as you want till you max it out.
Before finishing a side quest that doesn't trigger a cutscene, draw your weapon. Once your weapon is drawn, talk to the NPC that completes the quest. Once your character puts his or her weapon away, repeatedly hit A till desired level or gold amount is reached.
As with Dragon Age: Origins, place your most expensive item into your trash alone. Go to a merchant. Select sell and go to the trash tab. Hit Y and then nearly immediately press A. If you were successful the item you sold will have sold twice giving you extra money. To duplicate stackable items like potions purchase two or more stackable items. Do the above cheat. Enter into buy mode. Buy back all but one of the item you wish to duplicate. Repeat the cheat. Your stackable items will have increased for as many as you have sold. Example: Purchase ten potions. Place them in your junk pile. Perform the cheat. Enter the buy tab. Re-purchase nine of the ten potions from the buy-back tab. Enter the sell mode. Go to the trash tab. Perform the cheat. You will have 19 potions and their cost in coins doubled back to you.