If you want really anonymous and untraceable transactions, use Monero. It is based on ring signatures, which makes the sender, receiver and the amount being sent undetectable and the transactions untraceable by default. You don't have to use any "special feature".
I think that the anonymity capabilities of Monero are self-demonstrated by the following statement of the officials after the AlphaBay shutdown: "In total, from CAZES' wallets and computer agents took control of approximately $8,800,000 in Bitcoin, Ethereum, Monero and Zcash, broken down as follows: 1,605.0503851 Bitcoin, 8,309.271639 Ethereum, 3,691.98 Zcash, and an unknown amount of Monero."
I think that the anonymity capabilities of Monero are self-demonstrated by the following statement of the officials after the AlphaBay shutdown: "In total, from CAZES' wallets and computer agents took control of approximately $8,800,000 in Bitcoin, Ethereum, Monero and Zcash, broken down as follows: 1,605.0503851 Bitcoin, 8,309.271639 Ethereum, 3,691.98 Zcash, and an unknown amount of Monero."