Build points are the points that help determine your deck. Ok Attack deck has 20 card but those card have different build point that add up to 20. Apparently some card are worth 2 or more (these are the powerful by default), this results in a need to balance the attacks by adding 0 points (the fodder attacks).
Invisibility strike apparently is good for bypassing potentially damage reducing bursts, as you take the attack card and deal the basic damage. If you have a Viperlash, and you have Mipedian with Invisibility Strike in combat, you can just deal 15 damage just like that and you opponent can't counter it with anything.
I am an Enlightened Despot, not a tyrant.
But a dictator no doubt.