Blitzkrieg primarily relies on the Lightning Mech's extremely powerful Electric Whip, which can chain damage to targets and wipe out many enemies in a single attack. However, the whip is as dangerous to the enemy as it is to both your own mechs and mission objectives, meaning that the Hook and Boulder mechs are vital to position everything so that you deal the least collateral damage.
There are often times where the Electric Whip must be chained with your own mechs to ensure the greatest damage; do not hesitate to do so if it can prevent grid damage and does not kill a pilot. This is dangerous early on when the Boulder Mech has only 2 HP and will be instantly killed by the whip, meaning that only the Hook Mech can serve as chain damage fodder until reactor cores are obtained.
Remember that mission objectives, deploys, and ally units are also damaged by Electric Whip. The best missions to take are those without any entity objectives, such as killing a number of enemies or not taking grid damage.
The boulders launched by the Boulder Mech are key for positioning, as they can block emerging Vek, be used for chaining the Electric Whip, block projectiles and push enemies. Never use the Boulder Mech for lightning fodder unless it has more than 2 HP.
If Advanced Equipment is active, Networked Shielding is the best passive for the Blitzkrieg as it lets you freely zap through your own mechs with no reprocussions whatsoever.
Blitzkrieg benefits greatly from the following pilots:
Silica: Allows the Lightning Mech to fire twice per turn, making it extremely devastating in the late-game.
Chen Rong and Archimedes: Lets the Hook Mech move to safety after pulling a Vek into a chain.
Kai Miller and Morgan Lejeune: Allows the Lightning Mech to deal 3 damage early on, although it will make the Hook Mech take 2 damage when chained.
Mafan: Allows immediate access to the Building Chain upgrade piloting the Lightning Mech.