The Greek gift (Bxh7+)
The “Greek gift” is the bishop sacrifice on h7 (or h2): like the Trojan horse, it's a gift the king shouldn't accept… but declining it is costly too. If the king takes it, knight to g5 and queen to h5 set up a devastating attack.
Requirements of the pattern: your bishop aims at h7 along the b1-h7 diagonal; a knight can leap to g5; the queen reaches h5 quickly; and the opponent has no knight on f6 defending (a pawn of yours on e5 usually takes care of that).
The fine print: the g5 square must be safe for your knight. If the enemy queen or bishop can capture on g5 unpunished, the gift doesn't work. That's why it helps to keep the c1 bishop at home covering g5: if the queen takes there, you answer with the bishop and win queen for knight.
And note: the toughest defense is usually not to return to g8, but to flee with the king to g6. It also loses, but demands precise play. You'll see it in the free practice.
Guided example
You play the pattern's moves; the tutor comments on each step. If you stray, it rewinds and you retry.
Practice: execute the pattern
Against the engine, with an adjustable defender level. Win the position to mark it as cleared.