What happened to the first rule?

I dunno, but here's the second:

http://yugioh.wikia.com/wiki/Hero%27s_Rule_2

"Hero's Rule 2" has seen an uprising in side deck play lately, mostly in Infernities, occasionally in X-Sabers, and why not? It's quite a flexible card in such a grave-centric era.

People previously threw around the idea of using "Imperial Iron Wall" in the Infernity side deck, but it quickly became apparent that it's too passive a card for the strategy since it has to be able to sit on the field and has little disruptive power in its own right. It also disallows you from using your own copies of "Bottomless Trap Hole" and "Infernity Break" while active, and denying your own use of simple but powerful 1 for 1 cards such as these is painful. Sure, you could side them out to accommodate "Imperial Iron Wall," but is that really the best idea in most cases?

This is where "Hero's Rule 2" came into the picture.

On the offensive, you can use it to jam an opponent's "Infernity Mirage," "Infernity Necromancer," "Infernity Launcher," "XX-Saber Faultroll," "XX-Saber Ragigura," and more. On the defensive, you can block the likes of "D.D. Crow" or a "Gottoms' Emergency Call" that's trying to steal your monsters. Even better, it's a counter trap, so "Stardust Dragon" can't do anything in response! To top things off, it has no chance of messing with your own card choices, so it's easy to see why "Hero's Rule 2" has gained popularity and is an overall superior choice compared to "Imperial Iron Wall."

Use it.