ion's claw
The Lion's claw is the favorite variation of The Lion. It is the most agressive and least predictable variation. Black prepares for a solid attack on the kingside. Black's moves are always the same. Black wins many tempi and moves his Queen's Knight to the ideal square: f4. Black doesn't castle. White usually reacts by (incorrectly) sacrificing his Bishop or weakening his kingside. That is the moment when the Lion's claw reaches for the white King's throat. You gotta love it... 


1.  e2-e4     d7-d6 If white starts with d4 (or c4, Nf3, b4 etc) that's also fine.
2.  d2-d4   Ng8-f6  
3.  Nb1-c3 Nb8-d7  
4.  Ng1-f3   e7-e5 White doesn't play f4 and focuses on the centre. 
5. Bf1-c4  h7-h6 I like to play h6 here because I don't want white's Bishop to pin my Knight at f6. You can also play Be7 or c6. 
6. 0-0     c7-c6  This pawn move has two goals: to defend d5 against Nd5 and to prepare the attacking b5. 
7. a2-a3  Qd8-c7 White has to respond with a3 (or a4 or Bb3) because otherwise b5 follows. After Bb3 comes b4 and the Knight has to be moved, leaving e4 unguarded and white loses this centre pawn. 
8. Bc1-e3  Bf8-e7 White is starting to lose grip on the game. He doesn't know where to attack because black doesn't castle and therefore centres his pieces. If white takes e5 you of course take it back with d6. 
9. Qd1-e2  Nd7-f8 Black has nothing to fear and moves his Queen's Knight via f8-g6 to f4 where there is a beautiful square waiting for him. If white plays d5 don't take it. Let white take your c-pawn and take it back with b7. 
10. Ra1-d1  g7-g5 Black starts his attack.  Now white begins to panic and starts to clear the centre (dxe5). Just take it back with your pawn and the open d-line is no threat for black. If white plays 10.Nh4 you react with g6 (and then g6-g5) and another tempo is won. 
11. h2-h3  Nf8-g6 White has to make this move because he has to get his Knight to h2. This of course weakens his kingside. If white doesn't have a Bishop on c4 the black Knight can also go to e6 (=a bit better). 
12. Nf3-h2  Ng6-f4 The black Knight is where he is supposed to be. White has to take it with his Bishop because it is too dangerous. If white doesn't move his Knight (to h2) you can consider a pawn sacrifice (g4).
13. Be3xf4  g5xf4 You can also take f4 back with your e-pawn so your Queen is more involved in the game. I believe it is a little unsafe  because it leaves the black King a bit unguarded. Taking f4 with g also has the benefit of opening the g-line for the Rook. 
After this black can expand his domination by setting the half-open g-line with his Rook. After playing the Queen's Bishop black can castle and draw his other Rook into the game. Often you can plan a good attack with the g- and h-pawn. Meanwhile the white pieces can view from the centre how their kingside is being cleared away. I think this variation is particularly suitable for beginning chess players or beginning Lion's players because it is easy to play and very instructive for it's strategy. This variation is also very suitable for rapid- and bullet games. 
Here follows another game with the Lion's claw. Black knows how to deal with this variation, as he is one of the writers of the Dutch book 'De Leeuw, het zwarte wapen'. 
Roel Trimp - Jerry van Rekom, 1996 ; 0-1