You can play quite the vicious parasite, try mixing the grabby polyp part and the leech. Stick to enemies and suck the life out of them. If you are small enough you can even slip inside bosses and even normal enemies and eat them from the inside out.

The deep part is also useful for this as it passes through everything to let you reach out quite safely to suck the life out like a creepy living straw.

Try covering your head in polyps and boosting into a non-Cra'Than sipho!

We already have Polyps, Leeches and Energy Leeches. Isn't that already basically the full parasite package? Just use these and latch on. Would be great if it was possible to extract nutrition, though, currently all one can leech of is energy and health.