I think it would be cool if the Sphinx gained attributes by being in the presence of diiferent creature types, not necessarily all 3 at the same time. Controlling a Wizard would give it Curiosity, controlling a Dwarf would give it first strike (or something), etc.
Which creature types should I use, though? Again, I specifically picked clerics, shamans, and wizards because to me, they
don't feel arbitrary. Because they're all magic-user creature types, it wouldn't make much sense to give the Sphinx any pure combat abilities. If wizards grant a curiosity ability, clerics could grant Absorb 1, but that still leaves shamans. What should they grant?
I'll consider the idea, but I think that it would be pretty tricky finding the "right" three abilities to grant, plus it makes the card considerably more complicated. I kind of like it being a simple, flavourful card. The ability is weak in the big picture, but would be powerful if you had a deck optimized to abuse it, which is fun, in my opinion.