Since Smokebomb requires both the Activation cost(AC) and the Casting cost(CC) to be paid to renew the temporary cloak, it seems like AC+CC should be a low value.
Smokebomb +
Stealth 2 acts almost like Immaterial (the weakness to AoE is still important)
HP of 1 is convenient as a weakness and to make the Stealth'd creature (named Ninja) only visible after Pandemonium because it would die to other AoE
I would suggest -1Atk, -1 CC.
Stealth 2
Smokebomb
AC+CC=low
AC=
![Darkness :darkness](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/darkness18x18.png)
|1
CC=2
![Underworld :underworld](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/underworld18x18.png)
|1
![Underworld :underworld](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/underworld18x18.png)
Atk=3|3-4
HP=1
![Underworld :underworld](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/underworld18x18.png)
=/=
![Darkness :darkness](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/darkness18x18.png)
(nightfall would allow creature to be seen without Pandemonium)
![Underworld :underworld](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/underworld18x18.png)
=
![Air :air](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/air18x18.png)
or
![Time :time](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/time18x18.png)
based on name and theme for returning to hand.
Ninja:
![Underworld :underworld](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/underworld18x18.png)
=
![Air :air](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/air18x18.png)
(
![Aether :aether](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/aether18x18.png)
and
![Time :time](https://elementscommunity.org/forum/Smileys/solosmileys/../../../images/Misc/time18x18.png)
still would work but slightly less so)
Ninja could be Ranged and not be OP.