I'm not really sure what the purpose of many of the subtypes of ice is, to be honest with you guys. I get the whole barrier/sentry/code gate aspect, of course, but it's the titles like Tracer, Observer, Destroyer, etc that I'm a little lost on. The HB identity shed some light on the purpose of the Bioroid subtype, but that's all I've figured out so far.

A sentry - Tracer - Destroyer like Ichi 1.0 can be approached by a Sentry icebreaker the same way any other Sentry would, right? I'm pretty sure, but I want to double check.

Speaking of double checking, unless it's been tinkered, Crypsis is the only one (at least in the core set or that I know of) that can break trap Subroutines, correct?

EarthDefenseForce said:

Subtypes, whether it be on ice or any other card, have no inherent rules associated with them. They are merely identifiers that allow card effects to interact with a subset of cards. Some subtypes (most notably the three types most commonly found on ice) have a lot of cards that interact with them (the icebreakers), while other subtypes are only referenced by a few card effects, and some subtypes are not referenced by any effect so far (which may or may not change in the future), so they end up being merely flavor for now.

So yes, any icebreaker that can break sentry subroutines can interact with Ichi 1.0.

Wyrm is the second icebreaker that can break subroutines on any type of ice.

Another example would be the card Deus X which allows the runner to break any number of AP subroutines.

AP usually does damage (Data Mine, Heimdall, Janus, Neural Katana, Viktor 1.0, Wall of Thorns, Woodcutter).