with how weak the card is stat wise,and how few creatures 2 purity verore usually runs,i don't think it's all that good anymore.
as any creature in the block zone will shut this card down,were before it wasn't too bad if they blocked because you still got some value out of it.
This card is not unplayable or crap yes its ability changed and why should you be able to ensure you get an ability card that not right in it own way from my view. Saying if it got some value out of it still sounds like it ability should be similar to what it was like. Even if I die as long as I attacked I will generate you a lightening blast.
The ability had a faction advantage against Genesis that was the whole problem since genesis decks plus the faction is not something with loads of removal they carter around Artefacts, Self enhancement, Creation and other things. To deal with this was to add more removal cards but doing so I find that it minimizes the play style of your deck to deal with a single card. That is not even promising ether because you will have to rely on the RNG unlike Thunder Apprentice will be straight of in command with the possibility of the opponent having copies of Lightening Blast ready.
Note: Yes it is not 100% ensured but was a high chance still.
Old TA if it attacked and was blocked it would die and generate 1 lightning blast. If you then play the lightning blast you will have done a total damage of 7 from 3 total resources. This is BELOW curve. Standard for 3 resources is 8 or higher. (See consecrating angel, one of many, flame dawn purifier, etc.)
Old TA needed to generate at least 2 lightning blasts to be worth it.
New TA has a high potential to be a card that says 'spend 2 resources, deal 3 damage to a creature of an opponent's choice'. If it is played and left unblocked, yes you get a lightning blast, but as I mentioned before TA needs to generate 2 before you can break even. What this change does is ensure that TA will almost never generate 2 lightning blasts (what are the odds your opponent doesn't block it twice?) I would actually argue that masked initiate is a stronger card at the moment, just because its stats are closer to curve and it's health is above the first damage threshold (that means higher than 4 for anyone who doesn't know).