Magical Girl is only half of the magic themed .6 update. The other half is the Witch. This class is about using your time delayed spell effects to create combos, turning small effects like Hex of Lust above, which adds two hearts this turn, and two hearts at the beginning of next turn, into big gains.

The wand symbol means that the effect next to it the right will happen at the start of your next turn. For example, Hex of Transformation gives you a total of 4 TF, but half this turn, half the next. While at first glance, this seems much worse than adding 4 TF straight up as it interacts worse with doubling effects like Something in the Water, as well as potentially winning you the round a turn slower, if you combine spells you can get big payoffs.

For example, if you cast Unstable Offering before Hex of Transformation, that 2 TF will turn into 4 TF, as well as boosting the rest of your turn. An important thing to remember is that spells are cast in the order you played them. It's important to plan ahead for which spells you want to happen before others.

If you cast Spell Amplification after your other spells, it won't have any effect. But if you remember to get it off first, it can turn your turn from meh to amazing. Spell Amplification + Unstable Offering + Hex of Transformation might only get you 2 TF this turn, but next turn it will get you 16! (2*2 * 2*2)

And if next turn you cast a time vortex, you can do it all again!
But that's not all that's going on in the Witch transformation. Since you want to be playing lots of witch cards at once, you'll probably get to the theme bonus pretty easily right? Well for Witch, you need to play 6 Witch cards in a turn to get the bonus! And what's the reward for that? Well...

The Witch theme bonus is called The Ritual. If you complete the ritual, your magical prowess draws the attention of demonic forces, transforming you into a Succubus! As a Succubus, the petty squabbles of your previous mortal life are beneath you. What is your fight against the shadowy organization compared to the great game for the souls of all men? When you become a Succubus, the game is swept away. Your TF level, your body modifications, your other theme bonuses, none of it matters. All that matters is how far you can spread evil in the name of your demonic masters before you're either contained, or lose the last of your humanity.

As a Succubus, heart and shield work normally, but there's a new resource. The pentagram represents you spreading evil among the mortals. This is essentially your score. The higher you can get this, the better. The TF icon refers to your own TF. You start at 0, and it only raises by playing cards that give into your demonic taint. For example, the card Enthralling Gaze increases your TF by 5. The game ends if you reach 100 TF as normal. The cards in the buy piles don't change based on your TF level as a Succubus.

The other way the game ends is if you're captured and contained. Your previous enemies aren't going to let you roam free spreading chaos. The shadowy organization has banded together to try and stop you. If their containment reaches 100, they'll manage to capture you. Be sure to pay some attention to disrupting their efforts as you corrupt the mortal fools.
And that's the Witch transformation. The test build should be out soon.