Bioimmunity ignores biomunitions. Total Imunity ignores all kind of Special Ammunition. Both of them let the target choose arm or bts for saves without any requirements for that.
@Dr. Nik I'd suggest not trying to find any clear logic to these rules. It doesn't exist. Why isn't Bioimmunity included on the same page as the other immunities? The similarities between BI and TI is disturbing. It's also disturbing how each uses a different format. TI breaks up the same rule into multiple bullet points while BI does not. This line from Total Immunity: "the owner is immune to the special effects of the Special Ammunitions, treating them as Normal Ammunition." I've been reading the word 'them' as referring to the special effects. So I thought it would be a good exercise to follow this process. I wanted to see what the effects are for normal ammo. Then substitute those effects into Special ammo. NORMAL AMMO Roll Normal (N) Ammunition forces its target to make one ARM Roll per impact suffered. Effects Each ARM Roll failed against Normal (N) Ammunition causes the target to lose one point from his Wounds/STR Attribute. Critical hits with Normal Ammunition cause the target to lose 1 point directly from his Wounds/STR Attribute, bypassing the usual ARM Roll. This link, http://infinitythewiki.com/en/Types_of_Special_Ammunition doesn't have a list of Special Ammo. It did have a chart. But if we go by the chart, DA has no special effects. So a TI trooper should take two hits from this ammo type. To be safe, I followed the link for DA ammo. DA AMMO Roll After a successful attack using DA Special Ammunition, the target must make two separate ARM Roll. Effects Double Action (DA) Special Ammunition forces its target to make two ARM Rolls per impact suffered. The second ARM Roll is mandatory, even if the target fails the first one or falls Unconscious. Each ARM Roll failed against DA Special Ammunition causes the target to lose one point from his Wounds/STR Attribute. Critical hits with DA Special Ammunition cause the target to lose 1 point directly from his Wounds/STR Attribute, bypassing the first ARM Roll (the target must still make the remaining Roll). I noticed none of these ammo types have any "special effects" only "effects" in their wiki page. But the chart lists them as "Special Effects". Plus normal ammo only requires taking wounds from failed ARM rolls, not BTS rolls. Some ammo says to make rolls under the 'effects' and 'roll' header, while others say to do so only under the 'roll' header. There is a large number of inconsistencies here. After substituting the effects, DA ammo still has a "Roll" heading that states the target must make two rolls. The newly substituted normal ammo effects say to take one wound for each failed roll. So the result is TI troopers make two rolls from DA ammo? But if the intent is for the TI trooper to only make one roll...I'd suggest these rules undergo a lot more clean up. A good place to start is not by mentioning the effects of special ammo at all. All that needs to be said is any special ammo is replaced by normal ammo. That way the "Roll" heading is included in the rules change.
He's saying, "Both of them let the target choose arm or bts for saves without any requirements for that." So I can save a combi hit with my BTS if I have bioimmunity. Which i would never assume to be true reading bioimmunity rules in isolation. And I think @Dr. Nik agrees. Now based on the ruling for total immunity, I see how the same can be argued for bioimmunity.
I'm going to through in my 2 cents here. I think its important to note that while reading this rule there are no requirements. If there where it would read differently. The way I read this out is as such. If a unit with total immunity is the target of an attack, weapon, or rule that forces an ARM or BTS then the unit is immune to special effects of special ammo and treats it as normal ammo. In addition to being immune to special ammo as stated in the line above a unit with total immunity can choose between making and ARM or BTS roll, choosing the most advantageous. (for me and my interpretation, this is not an if the unit is shot at its in addition to the rules above because there are no requirements for this skill) For me the big question for intention would be the "In addition" remark. I don't think it is clear from my point of view. If the rule was stated like so: When a unit with total immunity is the target of an attack, weapon, or rule that forces an ARM or BTS and it uses a special ammunition type then the unit with total immunity can choose between ARM or BTS. To me, that would be much more clear. By writing it as "in addition" that is not worded as a cause and effect statement or and "if > then" statement. As it is, "in addition" to me means "Additionally" as it is written. I read it as such Additionally, players can choose between making an ARM Roll or BTS roll, choosing the most advantageous for them. Now if there were requirements in the requirement section this would be different. if it really is this way than a player can choose what type of roll they want without being affected by special ammo. Therefore canceling out the effects of Normal ammo and protheion. For me, the biggest problem for learning this game is there are some inconsistence in wording that are confusing. What I mean by this is that it would seem practical and logical to read rules that look like they should be played as a similar concept. But in practice read the same but play differently.
To add to what @Azuset said, and to reiterate my previous reply to @Dr. Nik The user is immune to the special effects of Bio-Munitions - including Shock, Viral (see Infinity: Human Sphere) and any others within the Bio-Munition Category - treating them like Normal Ammunition instead. However, player can choose to roll ARM or BTS. Bioimmunity has a single bullet point for the entire rule, which makes a stronger linkage between the two parts. It also uses "however" instead of "additionally"; this is not a technical wording by any stretch, but the way I read and interpret English it indicates that it's only relevant if the first clause has been completed.
The difference is the bullet points. Bullet points create distinct effects. In TI's case that separates the Special Ammunition effects from the ARM/BTS choice effects. In Bioimmunity they are in the same clause and therefore tie together as you propose they do for TI. The formatting differences are key here. "In addition" is in respect to adding a unique effect, not tying onto the first bullet point.
So you're choosing to disregard the "in addition" wording in TI as some anomaly not regularly(if ever?) repeated in the rules? How do you know what wording to disregard and what to take seriously?
More importantly, how can you treat each bullet as a separate effect, while simultaneously applying the requirements from the first bullet to the second bullet? If we treat them separately, then there is no requirement for when I can choose to roll ARM or BTS. You can't have it both ways. Can I roll ARM or BTS instead of making a PH roll? This is not a rabbit hole i want to go down. Look at how Protheon handles something similar with it's bullet using the word "Also": The target loses one point from the Wounds/Structure Attribute for every failed BTS Roll. Also, if the target has a Wounds Attribute, then the Protheion users increase the value of their Wounds Attribute by one for every BTS Roll the target fails. The Protheion users indicate this by placing a Power-Up Marker by their side It spells out the requirements for the "Also" bullet point. TI does not. Edit, I think this is the best argument supporting why TI only allows you to choose BTS/ARM when being hit by special ammo. CB should be able to clear this up very easily if they wanted to. @Koni Can a trooper with Total Immunity, that suffers a successful hit from a combi rifle, roll the save using their BTS attribute?
Even the game Examples in the rules appear to be in favor of TI working only against special ammo, combined with the other stipulations given in the rules. There are only 4 game examples given and ALL of them are about Special Ammo. I notice a clear theme. A BTS special ammo An ARM special ammo. A special ammo where TI doesn't work because the save isn't an ARM or BTS, Finally when TI doesn't work because the trooper isn't hit by special ammo.
