Syk has two different forms of shapeshifting, each with pros and cons. This image shows a full transform, partial, and then their base form!

In order to fully transform into a creature, they have to consume the DNA of that creature. Sometimes it's just eating them, but usually it's a drop of blood or hair or whatever else can be taken without notice. When they do this, their slime is able to fully configure itself into the target. The only constant is their eye. It is always purple, and there can only ever be one (Shape and size can change, though). It's the biggest tell. Syk also can't make much in terms of pigment, so most full transforms are more pale than they should be.

How long it lasts depends on how much of the target was consumed. It's also very energy intensive to keep up a full transform, which makes it more difficult to maintain.

Partial transformations are easier. Syk more or less guesses what a creature looks like and will approximate a form. Typically they keep some amount of tendrils, as these forms are basic and focus more on utility. Because they're a slime, it's more natural to use a tendril over hands, so it's a convenience thing more than anything.

Each type of shapeshifting has different uses. Most animals rely on scent over sight to identify other members of their species, so using an approximation is better in that case. Why transform 100% into a rabbit and burn all that energy when a rabbit really doesn't care what another rabbit looks like? When it comes to humanoids or other intelligent species, a full transform is better for blending in. Of couse, if something can't see at all, there's no point in shapeshifting. Same if someone already knows what they are, though Syk does enjoy their humanoid form.

They can also use their slime to create tools or other objects! The slime can harden or soften as needed, and it can approximate most materials :3