If your into long campaigns for a planet you've never even heard of then I recommend it for you. Planet strike is actually many types of games in one which allows you to mobilize your entire army in a castle breach type of game. The first game in the campaign (its basically a well develloped scroll campaign) which is called planet fall.
Planetfall is the initial attack upon the planets defences, in other words DDay 40 k style. Of course you get stratagems which give your army a so called one up on the enemy. Attacker gets firestorm, which is literally d6 +3 large blast markers of s9 ap3 death from raining fire. Basically picture the movie Armageddon when the asteroids hit Singapore.
Reserves come in on 3+
Any questions?