What opening should i choose?

um preparing for a tournament comin in two days, wanna learn a opening for black, should I go for the Scandinavian or the caro kann?

I like the modern variation of the Scandinavian defence, I also play the Nizmo-Indian defence

Very ambitious to learn a new opening in two days.

Both are fine. But why a new opening? What do you use to play against 1.e4?

It is nice though to have an extra opening when your normal opening needs repair.

The Caro-Kann is fully sound - the Scandinavian is dubious at best. That ought to give you the answer, but also, like someone else already mentioned, trying to learn a new opening two days before a tournament is ridiculous. It would be like if i started preparing for the Najdorf back on Wednesday for this weekend's tournament about 100 miles south of where I am. I have played the French for 29 years. Why would I prep a new opening for the weekend?

There is NOTHING dubious about the Center Counter Defense... i.e. the Scandinavain

Been there ... debated this ... and "Burnt the T-Shirt!"

That statement 99% of the time is belched out by 1.e4 players ticked, because that opening sidebar's there favorite opening(s) as White.

Please... don't retort some nonsense about no GM uses it... plenty of GM's play it that are in the 2400-2500 elo range... Because some top 50 in the world super GM ( around 2700) doesn't play it... that is not evidence that the defense is unsound.

Then there is the fact that 99.999% of us are not GOING TO BE GMs, IMs, or NM'S .... debating the professional manutia that "Super GM's consider when employing an opening ... is quite frank.... A COMPLETE WASTE OF TIME.

As for taking on a new defense days before an OTB... if your an average player, that is not advisable

Two days is just enough time to confuse yourself. Two months might be enough time. Play what you usually play.

The Scandinavian is completely playable.

It leads to a position very much like a Caro-Kann formation; with White's e-Pawn having been traded off for Black's d-Pawn, with a White Pawn on d4 facing Black Pawns on e6 and c6, with Black's light-squared Bishop outside the Pawn chain, with White having superior development while Black has the superior potential Pawn levers... all of that EXACTLY as in a Caro-Kann.

The main difference between the two (Scandinavian vs Caro-Kann) is that in the Scandinavian Black loses a bit of extra time - in fact not even that, just a suboptimal order of development - and in return Black gets to avoid some of White's most aggressive anti-Caro lines such as the Advance, the Panov-Botvinnik, the Tal Variation, and so on.

Don’t play the Dubious Scandy!

Your just throwing away your chess games!

Have you thought about playing the French?

I wouldn't normally recommend the Scandi but if you really want to learn an opening in 2 days I think it's a much better choice than the CK... the CK is huge and more common / more theoretical. However, the even better choice is probably for you to just play what you know.

You are better off sticking to whatever way you already play than starting a brand new opening now and trying to have it work in 2 days. Your opponents will likely be more familiar with the opening than you are. People who make up an opening themselves tend to become decent at it in a natural way, especially if the opponent tries to "punish" you and overextends themselves.

I don't particularly like playing against garbage people just made up themselves, but if they play a lot they tend to get good at it, so I would say that's your best option for now.