Ghostly Touch

Whenever an Illusionist attack you control is destroyed by phantasm, put a haunt counter on this.

Once per Turn Action - Remove a haunt counter from this: Until end of turn, this becomes an Illusionist ally with phantasm, base

and

equal to the number of haunt counters on it, and "Once per Turn Action -

: Attack". Go again

Rulings

From the Uprising release notes

The triggered effect is not once per turn, you put a haunt counter on whenever an illusionist attack you control is destroyed by phantasm, even if it happens more than once per turn.
The effect also triggers when an ally you control is attacking and is destroyed by phantasm.
You cannot remove a haunt counter if there are none on the card.
The activated ability has go again, but the attack does not.
When Ghostly Touch becomes an illusionist ally with phantasm, it loses all other properties until the end of the turn. It is no longer called Ghostly Touch, does not have the types Illusionist Equipment Arms, does not have 0, and does not have its card text. As such it does not trigger when an attack you control is destroyed by phantasm.