Complex sentence: Following this, Leonardo reappears at various points throughout Assassin's Creed II, decoding Codex Pages and constructing more devices, most notable of which is a flying machine that Ezio uses to gain access to the heavily-guarded Doge's Palace in Venice.
Split into simpler sentences: Following this, Leonardo reappears at various points throughout Assassin's Creed II, decoding Codex Pages and constructing more of Ezio's devices. Most notable of these devices is when Leonardo helps Ezio using the flying machine to gain access to the Doge's Palace in Venice.