a card with the word 'dark' in the name without any connection to
? XD
i'd re-word 'The creature's atk + def = X' to 'X = target's attack + HP'
The upgrade is a huge improvement: 1 less casting cost, 1 less cost to use, and 2 more healing.
I think that this'd mean that either the table is UP or the altar is OP, but it could be that they are both just a bit unbalanced.
this is not OP with any
card,
as GP would allow almost the same amount of bonus HP,
but also protects from the full final blow.
Just saying before some1 mentions it.
EDIT: I think it is fine if this triggers all death effects. The healing from sacrificing skeletons isn't much.