or else
With the assault of the king, you need a standard plan. You must have a clear picture of the standard scenarios. That way, you prune the tree of scenarios and the tree of analysis beforehand. You calculate the main line, and when you are happy, you calculate the alternatives (or else), when the opponent doesn't want to cooperate. When all alternatives are worse, you are good to go. White to move 3r2k1/p3b2p/3pbpp1/7R/1r2P3/1P1B2Q1/q5PP/B4R1K w - - 0 25 The standard plan of the assault contains two elements: breach the wall of the killzone invade What does the breach Rxh7 accomplish? it attacks Be7 it undermines g6 it allows the white queen to attack the invasion square f6 with tempo Black cannot afford to ignore the rook . He must take the rook (or else). The next move is 2.Qh4+, which is a double attack on the king and the invasion square f6. Another way to say that it is, the white Queen attacks f6 with an additional tempo (the check).