Runner must pay , in addition to the normal cost, to break each subroutine of each piece of ice encountered during runs on this fort.
Rez a region when you install it. Install a region only if you can pay to rez it. Only one region may be installed in each fort. Trash older ones.
There are some points you have to consider every time you build a deck. Which Ices or which Icebreakers go into this deck? When you
build a Runner deck you have to balance the cost of pumping the strength and breaking the subroutines. As a Corp you have the choice
between putting Ices with big strength and putting Ices with many subroutines into your deck.
Let us have a closer look at these two criterions.
Ices with a potentially unlimited number of subroutines (Food Fight, Sandstorm,
Gatekeeper, and even Hunting Pack and Minotaur) are
much better to rely on, as there is only a single card which can change the cost to break a subroutine: Crystal Palace Station Grid. If
you have the bits to install it on a data fort, all Ice on this fort will cost at least  more to get through.
Ice vs. The Breakers
For the following, assume a Crystal Palace Station Grid to be installed.
If you have  for a Colonel Failure you also have  for a Gatekeeper
with seven subroutines. And as there are actually people out there playing with Cyfermaster, it costs them 
just to get through this single Ice. If they prefer Skeleton Passkeys it still costs them  (or 
with enough Clowns installed). You may start considering the use of Endless Corridor and
A Pile Driver now needs  to get through the Wall of Ice,
and it is still the cheapest breaker with a breaking cost of [1.75] per subroutine (on this Ice). A Sandstorm with only five
subroutines costs  upwards. All other wall breakers start to get a much better understanding of the name of
the Toughonium Wall.
Sentry breakers already have a breaking cost of at least , except for Wild Card and
Forwards Legacy which are commonly accompanied by lot of Clowns,
causing a shortness of bits. All others need an enormous amount of bits to get through the "palaced" Ices. A
Food Fight with six subroutines costs an AI BoonAI Boon between  and .
Crystal Palace Station Grid has only one disadvantage. It is a Region. Your opponent will see it and know what could happen.
Even worse, you can only install a single one in a data fort, in contrast to the
Antiquated Interface Routines. But it still costs the
Runner the same bits to trash it as it costs you to install it. And  is really a lot for the Runner,
especially if he has paid a lot of bits to get through.