When you're ready to farm those transcendent sigil stones, it's worth understanding why level 17 is such a crucial milestone - that's when you unlock the most powerful versions (something many players miss by waiting too long). The enchantments you'll want to focus on are quite interesting, and i'll explain why each matters.

Chameleon 30% is probably your best bet because it stacks multiplicatively with other pieces (meaning you can eventually become nearly invisible, which completely changes how you can approach combat). Shield 20% tends to be more valuable than straight health boosts, since it reduces incoming damage rather than just giving you more health to lose. For magic users, that 50-point magicka boost is particularly valuable, since it affects your total pool rather than just regeneration.

Here's what i've found works best when farming: make a hard save outside the gate first, then create a quicksave right before grabbing the stone (this gives you a fallback if something goes wrong). The enchantments randomize each time you grab them, which is actually a blessing in disguise - it lets you keep trying until you get exactly what you want. While you're at it, keep an eye out for resist magic and detect life effects, since they become incredibly useful against the tougher enemies you'll face at level 30 (especially those annoying high-level spellcasters who can one-shot you if you're not careful).

Remember, these stones can enchant both weapons and armor, so think carefully about your build before committing to one or the other - you might want to save some particularly good ones for later use (i usually keep a couple of chameleon stones in my inventory for when i find the perfect piece of armor to enhance).