The game never is complicated.

The game never is complicated. Only people make it seems complicated.
Rules tell you how the game works.
And QnA tells what this card can do and can't do.
it is a game that sometimes the effect are going far beyond the games RULE! Most player thought the game is broken. Reality it is not.
From the origin of BS, we should understand the main character of first season named "Toppa" (breakthrough)... You know what this game will become...

"In your end step, do 1 more turn" and ll sorts of unimaginable effect...

There are a lot of QnA for every single cards with effect. Player can never remember them all. But they do share the same QnA in some simple Logic. Such as...
Thundermillion require opponent to destroy 1 spirits in order to declare block. Is a effect that overwrite the rule.
Cancer's attack require opponent to use 2 spirits to block its attack. Is also a effect that overwrite the rule.
Mean, their effect cannot stack.
"opponent have to destroy 1 spirits in order to declare block"
"Opponent have to destroy 1 spirit in order to declare block"
Logic explained, block is declared once only, so the second effect cannot activate again. And cancer's logic explained.