In order to properly assess the potency of a card like this one needs to really take a good look at the section of the rulebook that covers forms. What is a form? When does one change a form? And so on. Therefore, before I get into the nitty gritty of this particular card it is worth listing the various different types of forms that we have in the game right now:

◉ Alter-Ego - Every hero (currently) has one of these

◉ Hero - The opposite side of the Identity card

◉ Ant-Man (Giant)/(Tiny) - Hero forms reward swapping back and forth between them

◉ Spectrum (Gamma)/(Photon)/(Pulsar) - She also has several efficient cards that let her change forms

◉ Shadowcat (Phased)/(Solid) - A core gimmick for this hero, with many hero aspect cards that let her change form, including a once per turn action with no card cost

◉ Vision (Intangible)/(Dense) - Same situation as Shadowcat

◉ Wasp (Giant)/(Tiny) - Hero forms reward swapping back and forth, but Wasp also benefits a lot from Alter-Ego form.

With this listed we can see that the main two areas this card can be effectively utilised is specific heroes who have Forms as a part of their innate kit; which we will go into with a little detail later on; and Identities who switch from Alter-Ego ↭ Hero a lot (and even then you only do it when you are going from Alter-Ego ➔ Hero because this is a Hero Response. However, that second category of Identity switching heroes are overall less efficient than Heroes with Form switching because Protection is an Aspect that often wants you to get into hero form and stick there for as long as possible. There are some Hero cards that do let you switch up from Alter-Ego ➔ Hero and there is of course also Colossus who has Tough status cards as an integral part of his design (and loves defending instead of losing Tough) so it is not always clear cut, it depends how much the deck you are building values suiting up with an immediate Toughness in exchange for 2 cards.

With all of that written I think we can see that this card has a limited number of heroes where it can function in enough of a useful fashion; Wasp, Ant-Man, Vision, Spectrum, Shadowcat and Colossus being the front runners due to high synergies. One can also consider it in Groot because Tough has been updated to take priority over his Growth counters but it is also worth mentioning that She-Hulk has some innate form switching cards and likes to flip back and forth a lot.

This card is certainly not a generic staple; especially because using with heroes who only form switch on their natural "suit up" flip is a tall ask if you do not have some specific goal in mind for that Toughness. So outside of the heroes listed above (and any future Form switching/Toughness synergy heroes/strategies) I think you can leave this one in the box and choose other methods to tank/avoid damage in Protection.