Revived troops will glow purple. They do not count towards troops deployed; only the original troop(s) that was/were destroyed will count towards troops deployed. If the revived troops are defeated, they do not count towards casualties.
Priority of revived troops follow the order of their defeat. The most recently destroyed troops will be revived. For example, if two Heavies and two Zookas are defeated in that order and the ability is used at level 1, Dr. Kavan will revive two Zookas and one Heavy.
If a large troop is unable to be revived, or if not enough troops were defeated to begin with, Dr. Kavan will create Riflemen of the level that you can train to fill up the remaining space. For example, if a Grenadier and two Zookas are defeated in that order and the ability is used at level 1, Dr. Kavan will revive two Zookas and create four Riflemen.
Revived troops have the same stats as the original troops and will respond to Flares. They can even be healed by Dr. Kavan himself. They last until they are destroyed by defenses or the battle ends. If a retreat is called, all revived troops will stand their ground and distract enemy defenses, much like Critters.
Revived troops do not return to the Landing Craft, even if they survive the battle. The original troops will still have to be retrained.
Each use costs 10 more Energy than the previous one, with a starting cost of 8 Energy.
Using the Second Wind ability to start a battle with extra Riflemen can bolster your army for the entirety of the attack, especially if your army already includes Riflemen.
In the event of a retreat, Second Wind could be used to revive fallen troops who will stand around distracting turrets while your main forces escape.
In the event you lose an important troop in your attack, such as a Medic, you should activate the ability as soon as possible, lest said troop is not revived by the ability due to other troops' defeats causing them to be revived in place of the important troop.
Same goes if your Scorcher blows up since unless at level 4 or higher this ability can't revive a Scorcher, while a revived Scorcher may be invaluable to your arsenal.