Giving the controller of this spell full control over which permanents remain makes this significantly better than the average Wrath of God variant
It's the Mana Flare part
Red can easily generate mana advantage as well, be it through bursty rituals (Irencrag Feat), treasure tokens (Dockside Extortionist), free spell/polymorph effects (Fires of Invention, Tibalts Trickery), or the occasional outright mana dork/discounter/mana multiplier (Leyline Tyrant, Mana Echoes)
There are two different variants of this error
When any Dragon you control attacks, you get to draw a card for each attacking Dragon and then put a permanent card from your hand into play
You then get Lefou back to your hand and can exert Madam Mim to play Lefou again, ready her again, challenge again, etc