Can a Wyrm interact with an ICE that has strength 4? Starting with lowering its strength and using a Atman with power of 2?

Type: Program: Icebreaker - AI
Cost: 1 Memory Units: 1
Faction: Runner Anarch
Faction Cost: 2
3 [Credits]: Break ice subroutine on a piece of ice with 0 or less strength.
1 [Credits]: Ice has -1 strength.
1 [Credits]: +1 strength.
Fire and ichor...
Strength: 1

You would need to pay 3 credits to raise Wyrm's strength to 4, then 2 credits to lower the ice's strength to 2, then 1 credit per subroutine to break it with Atman.

To more directly answer your question: Wyrm can interact with an ice of strength 4 only if Wyrm's strength is at least 4.

Wyrm seems to come up a lot on this board, along with a few other common questions (such as 'can you use multiple icebreakers, or how long do icebreakers keep their strength for). I realise that these questions are answered in the official rules and FAQ, but may I suggest creating a sticky FAQ thread? Could be updated if new cards generate a lot of repeats on the same questions as well.

I'm not certain people who don't search before posting are going to read a stickied thread either.

Yeah, fair point. There are like, 11 pages currently though; a sticky might head off some of them at least. I guess it'd be down to an admin to decide one way or the other though - I assume like other PHP boards you need privileges to make a sticky?

I'm pretty sure that's the case. Stickied threads seem to be pretty rare on this board.

****, I just realized a Wyrmosaurus isn't possible :-( Apart form Dinosaurus and Personal Touch, there aren't any other cards that boost ICEbreaker strength, are there?

Well you can still make a Wyrmosaurus, it's just not a particularly useful combo. Generally speaking, Wyrm seems to exist as a card to support your fixed-strength breakers by bringing them into range. However, as Wyrm starts at a paltry Str 1, boosting it to relevant Str of ICE before then LOWERING the ICE Str into breaker-range (for Yog, Mimic or Atman) gets expensive fast.

Seems to me that Datasuckers are better support for your fixed-Str breakers (unless someone can successfully lock you out of all centrals then purge viruses). Best recovery from that then is either Wyrm, Parasite, or Grimoire-Datasucker recursion (though clone chip, scavenge, retrieval run etc) followed by surge.

Well you can still make a Wyrmosaurus

Wyrmosaurus means Wyrm hosted on Dinosaurus, which is not legal since you can only host non-AI breakers on Dinosaurus.

Ah, forgot that restriction. Ignore me then!

Well, I could still use a combination of Datasuckers, ICE Carver(s) and Personal Touch to kinda achieve the same effect, but somehow I doubt that'd be efficient, Influence limitations aside...