Board Thread:LOC General Discussion/@comment-6011882-20130225173228/@comment-5706972-20130226201743

The Raid line I use is 3 Raid cards and 2 heavy hitters. Up to 3 Raid skills can activate in each battle. If you don't hit 'skip', you will see that your line attacks 5 times, with the boss retaliating after each attack. Only 1 Raid skill will activate per attack, but up to 3 may activate across the 5 attacks (all within the same battle). The boost provided by the skill depends on whether it is the current raid (large boost for reg, and great boost for ex) or a past raid card (med boost) and what skill level it is.

To answer your second question: that is up to you. Efficient cards with low power will need to battle more times. This may not sound like it costs anything more than additional time, but remember, every battle costs your front line (attack + 5)/2 - so more attacks costs you more atk power (and thereby dropping your efficiency).