Tricastle is a mini-boss from Mega Man 10, found in Blade Man's stage. It is a castle made up of three sections; a large, center gate with two towers on its sides. Each section has a hole where a pair of eyes can be seen peeking out, which is also the weak spot of each section. Shoot this area on all three sections to destroy Tricastle.
The gate opens and closes, releasing platforms with spiked edges while it's open. These platforms are used to to reach the other two towers. Once the gate is destroyed, it will remain open and continue to release platforms. The two towers are equipped with turrets that shoot at Mega Man. Once the eyes are destroyed, the turrets will be disabled. When all three sections are destroyed, the castle will humorously raise a white flag of surrender and slowly collapse.
One really effective weapon against this is the Solar Blaze, which, if it attacks any upper tower, it will also attack the other one.