Metallizing Parasite - Soltite

You can only activate one of the effects—either the effect to equip this card to a monster, or the effect to Special Summon it—once per turn.

The effect "Once per turn, during your Main Phase, you can equip this card to a monster you control as an Equip Card" is an Ignition Effect. It targets 1 face-up monster in your Monster Zone. (The effect "If the equipped monster would be destroyed by battle, destroy this card instead" is an effect applied while "Metalzoa" is treated as an Equip Spell Card. This effect does not start a Chain Link.)

The effect "You can unequip this card and Special Summon it in face-up Attack Position" is an effect that can be activated while "Metalzoa" is treated as an Equip Spell Card. (This effect starts a Chain Link. It can only be activated during your Main Phase. It does not target.)

The effect "While equipped with this card by this effect, the equipped monster cannot be targeted by, or destroyed by, your opponent's Effect Monster effects" is an effect applied while "Metalzoa" is treated as an Equip Spell Card. (This effect does not start a Chain Link.)

"A monster can only be equipped with 1 Union monster at a time" is not treated as an effect.