I don't see a lot of use in this card though.
It dies easily to shields and any CC when vulnerable, and it deals 5-6 damage over the course of 2 turns. Doesn't fit in rush and doesn't fit the theme of stall either.
Also, if Cosmic worm is hit with poison, or freeze, or procrastination, does that turn when it's invulnerable to attacks still cause it to be damaged/wear down the counter?
And to be honest, it's just a worse immortal.
as i said before, this card has a very high chance of striking the opponent twice without being neutralized by a spell such as lightning or fire bolt, thats its primary use, and what makes this card special is that, before it attacks you can bless it, give it momentum, etc.
before starting its phasing cycle, which then makes the card even more lethal due to its phasing.
as for the shield effects, thats the reason why i put 3 hp on the unupped and 2 hp on the upped,
lets say cosmic worm (upped) attacks but gets poisoned by carapace shield, it disappears, however the poison will still effect it even if its gone, so when it comes back it would have 1 hp left, and as soon as it attacks this turn, it dies from the next poison damage.
and if it freezes, it normally comes back frozen but unable to attack, so it stays there if doesnt attack as it is frozen.
i think i may have to change the unupped hp to 2hp as well now that you´ve made me think.
BTW an immortal is immortal, it cannot be targeted, cosmic worm can be targeted, so it isnt an immortal but rather a hard target (in concept and in some cases in the game) so i don´t understand what you mean by "worse immortal".