I think that the reasoning is that, if there's an Uncommon that summons
Wicked Ritual when playing the Rare would be ideal, Wicked Ritual itself would need to be rebalanced as an Uncommon card.
Titan's shadow, Uncommon 14g
If your tower was reduced by at least 20 last turn:
Summon Wicked ritual
else:
Titan tokens: +25
Your revision to the card alleviates that somewhat, since it no longer looks at what's in your hand and instead depends on the opponent doing something (dealing 20 tower damage). It's also good that Titan's shadow and Wicked Ritual share a resource in their collective cost. But it still needs to be questioned whether this makes playing Wicked Ritual too easy for the way it's currently balanced.