You can activate this card if a Spell/Trap Card that destroys a "Morphtronic" monster(s) you control is activated, even if it is a card such as "Torrential Tribute" etc. that does not target.
When "Smashing Ground" or "Fissure" is activated, even if "Morphtronic" monsters are the only monsters on the field, you cannot activate "Morphtronic Forcefield". Also, if "Torrential Tribute" is activated while there is a "Morphtronic" monsters on the field, "Morphtronic Forcefield" can be activated in Chain. Furthermore, when the opponent activates "Mirror Force", if there is a face-up Attack Position "Morphtronic" monster on your field, "Morphtronic Forcefield" can be activated in Chain.