Costing only 1 less mana seems to be too much to enjoy playing this card for me.
I would like to test it to a max of 2 mana less. So first turn it would be 1 mana cheaper, and 2nd turn it would be 2 mana cheaper. And then it would stay at 2 mana cheaper, the way it stays at 1 mana cheaper in this version of the card.
Not enjoying this version of this card the way it is now. It just feels bad playing it. Because not only do you take too much self damage from the portal but you also don't get enough value and upside to balance it.
At least in its original form, it had high risk high reward. This version just feels too much risk and little reward/value.
It might even be worth considering capping the self damage to max of 2. It's just so brutal, it's big reason why i don't enjoy the card that much.