1. forms and form changing
2. fighting
3. regeneration
4. communication
5. hacking
6. special abilities
FORMS AND FORM CHANGING
Lucky you, you've now got three forms to play with. For the most part, you'll be spending most of your time in the most humanlike one for convenience's sake. It's easier to communicate and get by. Plus, the identity confusion can be fun. In this form you're still stronger and faster and generally better than most people, so it's not a completel loss. You'll have the abilities that your host character had as far as skills go, and amplification of their class traits. Any particularly odious personal habits may also be present.
Switching to the Avatar form is a fairly standard action. The actual Avatar only exists on the second level, which means that most people don't get to see what's killing them. While it takes a tag to switch forms, since normally you're moving faster than your target to begin with, switching to an even FASTER form means that you can still spam them with death while they stand around google-eyed. While it's possible to communicate in basic form, it's more difficult. Think yelling down a tunnel. The mind is somewhat distracted due to function-related issues, but because this form was attached to a host there's still the ability for human reasoning included.
Switching to the True form/oldschool/whatever you want to call it is a standard action, but one taken during periods of great stress. This form is usually a sharp improvement on the Avatar form in most ways, but it is a perfection, and thus there is little by way of reason or other annoying human traits. Destruction is the name of the game and functionality comes to the fore. Still takes a tag to change, but usually when this comes out shit is coming down and so it's hard to say whether your opponent will be standing still. Usually when this one comes out is when death needs to come fast and efficiently.
FIGHTING
The beginning of every fight starts in the host form. For the most part this form should be sufficient, unless a foe is being particularly annoying. Physical fighting is probably norm, although use of skills is possible. Skill trigger still has a recharge period, though, but since you can punch people through walls it's not like you're paralyzed while waiting for it. Any weapon styles that your host had, you can use, so you can clobber people close range, or you can pull out the scythe and keep them at long range. While usually stronger, faster, and more sturdy than most people, these are distributed along the lines of your host's class. So you may have a better endurance, but it may be less than your siblings due to class issues. That's the main drawback of this form - there's no standardization of abilities.
Once the fight moves on to Avatar form, things get a little interesting. The Avatar's skillset takes the fore, and the fight proceedes according to that Avatar's specialty. Traits are tweaked a little bit - while still skewed according to class lines, the difference is not that great. It's all on the Second Level, so projectile attacks that hit innocents will remain invisible, leaving people to freak out at SUDDEN DEATH. Within time these projectiles will fade, as the data is recalled and recompiled due to regeneration cycles - or in the case of Skeith's cheap swords, at whim. While fighting in Avatar form, people who can't see the Avatar will only see the physical body, often doing strange things, other times just standing around looking bored. While the form is essentially invincible due to Protect cycles, eventually the energy runs out and the form must be dropped to regenerate. Also, cosmetic damage can occur due to the stylized designs of many of the forms, which can lead to complications.
However, when the True form comes out it's go time. Impossibly strong, impossibly stalwart, and yet still speedy, this form is good at killing and little else. The attack set changes up again, usually to create as much collateral damage as possible. Some attacks become undodgeable, others just hit super hard. Some develop shields, others can use regeneration magic. The primary advantage of the True form is that it is essentially invincible - unlike Avatar which internalizes damage from an energy pool, this form internalizes it and dissipates it. Only through data drain can this form be defeated.
FIGHTING - Data Drain
All forms are succeptible to data drain. It's the one common weakness. First a Protect Break must be achieved, which requires extended periods of being beaten on. Once the Protect Break has occurred, there is a short window of weakness in which the data drain can be performed for actual effect. The main effect of data drain is that the Epitaph will be removed. If the Phase is in any other form than host, they will drop form immediately and pass out. If in host form they will experience extreme pain before passing out. Host form will suffer physical complications due to loss of Epitaph, including loss of any special abilities associated with that Epitaph.
Regaining the Epitaph can be a bit more difficult. Without a second party or other form of patcher to reintegrate it, full potential cannot be regained. Anyone skilled in Harald System, or a sibling can replace it. Once an Epitaph has been reintegrated all restrictions are removed.
REGENERATION
Basic regeneration is possessed in all forms, although forms not in use regenerate much faster. In host form, this regeneration is essentially accelerated healing, of any sort of injury. With enough rest or disuse of form, anything can be regenerated. The energy pool, as well as any cosmetic damage, is what regenerates in Avatar form. Technically True form possesses constant regeneration due to how the damage is dissipated in a pre-data drain state. Regeneration will not function if special abilities are locked down.
COMMUNICATION
Obviously the primary means of communication is in spoken language. This allows communication with everyone. However, there are times when spoken communication falls a bit short, when discretion is necessary, over long distances, or in team manoevers. Fortunately, there are other options. The first option is known as modulation. This works well over long distances, transmitted similarly to a radio signal, but also is just as good when just needing to keep what is being said a secret. In host form, modulation sounds smiliar to a modem, making it an effective way to not only prevent people from understanding, but to clear a room. In Avatar and True form, it is essentially a soundless transmission due to proper possession of transmitting protocols. The benefit of modulation is that in True form, when no spoken communication is possible, one can still modulate to those who can perceive it.
The other method is a more instinctive, nonverbal method based on body language and perceived procedural access/variable inheritance switch. Think something like pack dynamics among wolves. The movement of head, eyes, projected data or exposed variables can make a statement to those who can perceive it.
It of course must be said that if special abilities are locked down (such as through loss of Epitaph or sundry Template punishment) that these methods will not work.
HACKING
Being a data creature, it is almost impossible to keep a Phase out of something unhackable. They just understand innate hacking systems too well. Being able to think faster than a human coupled with extreme reflexes means that they can usually weave their way through any sort of protection, or punch through if they feel like making a point. Likewise, they are also rather impervious to being hacked, apart from by those who have very strong knowledge of data systems. However, Harald System will protect itself from outside unwanted intrusion in any way possible, which means that the various levels of forms can be utilized to defend from or attack intruders. The methods of hacking will depend on the Phase in question and what they are trying to do. Calling data from far away can be achieved by modulation, while engaging someone who is resisting being hacked may mean data is ripped out.
SPECIAL ABILITIES - Familial Sensing
All family members are "linked" in a way that they can "feel" or "sense" each others' existences even without being in the same room. If something happens (humanization or death), all family members will be aware of that loss even if they don't know how it happened. This does not provide further data without actually being present and scanning.
SPECIAL ABILITIES - Scanning
One of the most useful general abilities, scanning is what it sounds like - non-intrusive detection. Among other data constructs it can become intrusive due to reading their operating RAM. Essentially with this, one can determine basic information about the things or people around. With data constructs not protecting their running processes, or with a bit of focus and pushing even if they are, one can read their minds.
SPECIAL ABILITIES - Interfacing
By transmitting a specific signal two Phases or a Phase and any data device can interface. In this manner, data can be swapped around between Phases, or parsed or altered on a terminal. Data can be uploaded, or memory or procedures can be swapped or installed. More personal data can be shared, such as memories, if both parties are conscious during interfacing.
SPECIAL ABILITIES - Resource/Procedure Sharing
Due to being similar inheritances of the same subprogram, most procedures can be swapped around when necessary. A unique procedure or function call can be loaned or borrowed with a bit of tweaking to ensure proper variable passage. Resources such as RAM or base memory can be shared as well, provided the giver does not need it for anything. An interface must be established before such transfers are possible.