No, this is not a good idea, it will make thunderstorm too OP. Thunderstorm has already its uses; good against every creature with 1 hp, especially in masses; Shard of Focus, Malignant Cell, Photon|Ray of Light, Seraph, Phinix|Minor Phinix, Skeleton, Ruster, Schrodinger's Cat (unupped), Forest Spirit, Lycanthrope|Werewolf, Dragonfly|Damsefly, Virus|Retrovirus, Vulture, Deathstalker (unupped), Parasite|Bloodsucker, Ash Eater|Brimstone Eater, Lava Golem|Lava Destroyer, Deja Vu, Fate Egg, Dune Scorpion (unupped), Purple Nymph (unupped). Now, if you have two of those, you can play them on the same turn because of their low cost, so you can also kill creatures with 2 hp in masses (Mind Flayer, Crysaora, Ruby Dragon etc.). I don't think it needs any buff at all and as a permanent is OP. Many of you may think that since permanents like Fire Shield or Thorn Carapace deal mass CC damage each turn (or spells like Plague and creatures like Retrovirus), then why not Thunderstorm. The answer here is on the price of Thunderstorm (cheapest CC around) and its element (Air) which IMO has already strong and cheap permanents (Owl's Eye, Wings, Fog Shield, Shard of Freedom) and doesn't need more of these.