Yooka-Laylee and the Impossible Lair

The reason the description is worded like that is because Trowzer tells you that if you lower all five of his paywalls he'll give you a fourth tonic slot. After you pay 71 total T.W.I.T. coins to lower all his paywalls and then another 30 T.W.I.T. coins to him at his house in the desert, you'll get a fake fourth tonic slot. It's a tonic that, when equipped, gives you a fourth tonic slot, thereby rendering itself useless.

Getting a real fourth tonic slot requires you to collect all 200 T.W.I.T. coins. After giving Trowzer the 30 T.W.I.T. coins at his house, you'll have to give him your remaining 99 T.W.I.T. coins and you'll get a real fourth tonic slot, unlocking this achievement. Refer to the World's biggest T.W.I.T. Collector (50G) achievement solution for more information on finding all 200 T.W.I.T. coins.

The reason the description is worded like that is because Trowzer tells you that if you lower all five of his paywalls he'll give you a fourth tonic slot. After you pay 71 total T.W.I.T. coins to lower all his paywalls and then another 30 T.W.I.T. coins to him at his house in the desert, you'll get a fake fourth tonic slot. It's a tonic that, when equipped, gives you a fourth tonic slot, thereby rendering itself useless.

Getting a real fourth tonic slot requires you to collect all 200 T.W.I.T. coins. After giving Trowzer the 30 T.W.I.T. coins at his house, you'll have to give him your remaining 99 T.W.I.T. coins and you'll get a real fourth tonic slot, unlocking this achievement. Refer to the World's biggest T.W.I.T. Collector (50G) achievement solution for more information on finding all 200 T.W.I.T. coins.