Xyz-Raypierce

The effect "You can banish 1 Dragon monster and 1 Wyrm monster from your GY; Special Summon 1 'X-Ray Pierce' from your hand or Deck" is an Ignition Effect. (This effect does not target. When activating this effect, you banish 1 Dragon monster and 1 Wyrm monster from your GY, for a total of 2 monsters, as the cost.)

The effect "Special Summon 1 'X-Ray Pierce' from your hand or Deck" is an effect that is activated while "X-Ray Pierce" itself is face-up in the Monster Zone, and it Special Summons 1 copy of "X-Ray Pierce" from your hand or Deck. (This is not an effect that activates in the hand, etc.)

The effect "②: If this card is sent from the field to the GY: You can inflict 500 damage to your opponent" is a Trigger Effect that activates in the GY. (It does not target. It can also be activated during the Damage Step.)

You can activate the "inflict 500 damage to your opponent" effect not only when "X-Head Cannon" is sent from the field to the GY by battle or card effect, but also when it is sent from the field to the GY as a Tribute for an Advance Summon or as a cost to activate a card effect.