Tahm Kench is a hard Champ. It's challenging to master it even when Riot says that his difficulty is "Moderate." There are many things to consider when using Tahm Kench. He can get reduced quickly while also having some counters that can completely mess with Tahm's strat. If you have enough patience, you can climb with him, but there are many more manageable and more robust options if you want to climb in your Ranked Matches quickly.