Hee! Nice!

I think the final option could be a bit better. Considering this is a mythic Blightning. I guess three-for-one card advantage is a bit much for a 4-mana spell? But this is gold and mythic, and Concentrate is uncommon, so no, I stand by my claim: I think this would be fine if the third option made the player discards two cards not just one. That way you get a 3-2-1 progression too, which reads a little nicer than 3-1-1 when the original was 7-7-7.

Eh, I'm not a very big fan of using Mythic as an excuse for making something strictly more powerful. Plus, this card could easily be rare; I really only called it mythic because of the association with a known planeswalker.

I'd say the last mode is comparable to Blightning, and this card costs more than Blightning. My research on charms shows that charms typically cost 1-2 more mana than their individual modes would cost, and/or are more color intensive, as a versatility fee. So I think this is a reasonable place for this card.