Compatibility is another important and dangerous feature of the Zodiarts Switch, as when a Zodiarts Switch is first activated by one who is incompatible with the switch, it backfires on the Switcher, such in the case of Jiro Iseki, who is rendered comatose after activating an incompatible switch. Conversely, a Zodiarts Switch will reach the "Last One" state when the user is overwhelmed by their negative emotions to the point that they no longer wish to be human, with the switch announcing "Last One" in the voice of the Horoscopes who provided the Switch. A Last One Switch also changes its appearance, growing spikes and an eyeball-like structure, as well as changing the position of the button. When the Switcher activates the Switch at this point, the transformation becomes irreversible as the Switch drains its Switcher of their conscious mind and uses it to become a Zodiarts permanently. The Switcher's empty body is ejected from the Zodiarts, covered in a cobweb-like substance. In this state, the Zodiarts becomes extremely powerful and can only be defeated if targeted at point of its body where the Zodiarts Switch is located. In some cases, the "Last One" state doubles as a pupa state where certain Zodiarts can evolve further into one of the Horoscopes once the Resurrection Star begins to glow, absorbing their original bodies to remain human. Should a person have latent exceptional compatibility with a Horoscopes Switch, a regular Zodiarts Switch might evolve into a Horoscopes Switch the very first time it is activated, allowing its Switcher to skip the Last One state altogether and instantly become a Horoscopes-type Zodiarts.
Fighting a Zodiarts in its Last One state, a Kamen Rider can use one of its Limit Break finishing attacks to destroy the monster's body and get the Zodiarts Switch. Once properly switched off, the Zodiarts Switch will vanish into a singularity, returning the user's mind to its body.