What a cool card! It is probably the most unique card in the game to date. And what interesting opportunities it presents!!! In my mind, there are two main reasons to use this card.

1. Switch from an ID with a deck building or first turn bonus to an ID that will help you throughout the game. This would include Andromeda, The Professor, and excitingly Valencia. These IDs all have a powerful ability but once the game has started, they no longer provide any benefit (besides the link on Andromeda). Playing as ole Prof, filling your deck with powerful programs, just to then switch to Kate to help pay for the installs would be a good choice. I think this will become the most common use for The Professors one influence from here on out; and I think we may see some interesting and effective decks.

2. Switch from a high influence ID to one with lower influence. With this card you can squeeze a few more pips into your favorite IDs like Iain or Rielle. If you were to switch from Ken to Iain, you would be netting 6 more influence for Iain, a huge boon for him!

That being said, you may find yourself including this card under other circumstances if you happen to have a spare influence point to spend. Perhaps you can start as Nero for the early game pressure then switch to another ID once the game has progressed. Because the great thing is you can choose which ID will be best based on how the game is going. Maybe you planned on switching to Iain, but are currently crushing your opponent. In that case, maybe switch to Gabe to reimburse you for those HQ runs.

The card does have issues though. It costs an influence point, there aren't many ways to tutor it, and you can only include one in the deck. The latter two points especially present a problem. If you build a deck around it you may be left high and dry if it just happens to be sitting at the bottom of your stack. Logos is the only reliable way to get this card early that I can think of and so would be a good include if you are relying on Rebirth (it's not going to work with The Professor though :/ ).

Because of the preceding, I'm especially looking forward to using this card to switch from Andromeda to Iain. This switch would give you the first turn benefit of Andromeda with the potentially powerful ability of Iain. And you'd be stuffing 4 more influence into Iain. Oh, and you have a decent chance of drawing Rebirth early with Andromeda, or at least of getting a Logos.

So in conclusion, this card has a lot of potential and will be a lot of fun to use.

I think in any other game, Rebirth would be a fun, cute card that would let you think your way out of particular match-ups, or transition between phases of the game.

For example, Rebirthing from Kabonesa Wu into Jesminder or Kit after getting set up is a neat way to spend your influence and deck slots. And the ability to choose a different identity based on the situation offers a lot of fun decision points.

However, I think this design is a total mistake in Netrunner, for a couple reasons:

1. Identities that are blank after the start of the game: Identities like Andy, Val, or even The Professor have text that is only active when the game begins (or before) and are essentially blank afterwards. Because these Identities exist, it is a no-brainer for them to run Rebirth (except maybe the Professor) because it is always useful to them, even on turn 1. They have nothing to lose and everything to gain from including it in their deck. Compare this to Kabonesa Wu, who would need to hold onto Rebirth in hand for at least a few turns before using.
2. Identities are balanced around link and influence: Some Identities have stronger abilities than others, and as such have been balanced in other ways, namely now much link and influence that identity has. Omar Keung has a very strong identity ability, and as such has only 12 influence. This is meant to curb decks that use that Identity, because if he had 15 influence, he would likely be considered stronger than several other Identities. Kit has only 10 influence, because her ability to turn ice into code gates is very strong. Rebirth lets you play as these notably stronger identities, who are balanced with a downside, without the downside.

Because of these two factors, Rebirth allows Val, who has a strong abiilty that is notably blank after the start of the game, to use Omar's powerful identity ability. The player receives the upside of Val's ability and influence, with the upside of Omar's central-targeting power.

This, combined with Rebirth's "Limit 1 per deck" clause results in swingy matches where sometimes you're playing against Val (who is just fine in her own right) and sometimes playing against Omar with 15 influence, and you have a bad pub. Sometimes you're playing against Andy, and sometimes you're playing against Leela who got to start the game with a 4 extra cards in hand. For these reasons, I think Rebirth is a good example of bad design. Unfortunately, being poorly designed and slightly frustrating is not enough to warrant Removal from the game for now.

So one of the most apparent uses for this card would be to do something like start the game as Andromeda: Dispossessed Ristie to get a nine card opening hand and then turn into Gabriel Santiago: Consummate Professional or Leela Patel: Trained Pragmatist or whoever would be best in your current match up. Out of all the runners I think this works best with Andy since her ability is her opening hand. After that she's not doing anything for you.

For the other factions I think this is a harder card to want to slot in. Maybe if you're playing Kate "Mac" McCaffrey: Digital Tinker and once you have your rig all set up then you might want to rebirth into Rielle "Kit" Peddler: Transhuman for easy code gates or Jesminder Sareen: Girl Behind the Curtain for tag protection. Chaos Theory: Wünderkind could make good use of it since her best asset is the 40 card minimum meaning you can have a very tight deck and then rebirth into someone with a more useful ability, like Kate or Kit.

This is stupid good in Anarch. Most of their faction Id's have been treated as plug and play for a while now, save for a tech choice or two (Excluding Noise.) Now you can start a game as Reina, Quetzal, Valencia, or even MaxX and then transition to Whizzard or Edward Kim as the game goes on. As for other factions, I think Criminal is going to be the faction where Rebirth is used most. The Professor might use this to transition to either Kit, Kate, Chaos Theory, or Nasir, but I'm not holding my breath.

I have a question, with Rebirth can I make a deck with The Professor: Keeper of Knowledge. Using his ability then swap him with say Kate "Mac" McCaffrey: Digital Tinker and use her. Does it matter if the deck is too small for their min deck size or the influence exceeds, the new ID's. With now owning Rebirth and seeing useful for situations like this I just want to know if this is viable or is illegal to do in the world of Netrunner.