Lava Tubes | Magma Tubes (damage scaling)

[OdinVanguard]

Hi all, I just posted this card topic, but I am still trying to work on the damage scaling.
Lava Tubes | Magma Tubes

Spoiler for Card Images:

The function is similar to a catapult, but rather than killing the creature and dealing damage immediately, it increases the attack damage the creature deals (also automatically unburrows it and gives it flying).

My current idea:

• The creature will deal 2 times its attack damage plus catapult damage (based on hp)
• Catapult scaling is given as: (hp * 100) / (100 + hp)
• Unlike catapult, the creature deals damage as a normal attack at end of turn and then dies
• Creature becomes untargetable (to prevent abuse)
• Any effects that would prevent its attack are ignored (shield effects still get applied)
• Overlaying the creature with some kind of fire effect would be cool

Examples:
Antlion: 2|3 -> attack + catapult = 5 -> deals 10 damage on attack then dies
Shrieker: 8|3 -> attack + catapult = 11 -> deals 22 damage on attack then dies
Graboid: 4|3 unburrowed -> attack + catapult = 7 -> deals 14 damage on attack then dies
Devourer: 0|2 -> deals 4 damage on attack then dies

This is just one idea though, I'm open for pretty much any kind of damage scaling scheme to make it useful and balanced.
Having the extra damage be spell damage may be an option as well (to help ensure some gets past shields)

[rickerd]

What do you mean with 3/4 uses

[Calindu]

What do you mean with 3/4 uses

Spoiler for Captain Obvious:

On topic: It really looks UP, since you need a burrowed creature, maybe make it cost less(either effect or card).

[OdinVanguard]

How about a cost of 1 for each and lower cost on upped to 1 ?