Will this combo work since you aren't targeting the Progenitus directly?
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Is the question "Can you use Riptide shapeshifter's ability to put Progenitius on to the battlefield?"If so, yes that works. Riptide does not target at all.
Don't just post a few cards and ask "Does this combo work?". We don't know what you're trying to use those cards to do unless you explain it to us, so make sure to do so before asking us if it works. (You'd be surprised at the odd things people sometimes think their cards do.)