The Tughlaq King known as the "Wisest fool" was Muhammad Bin Tughlaq.

Muhammad Bin Tughlaq was the third ruler of the Tughlaq dynasty in Delhi Sultanate, who reigned from 1325 to 1351. He is often referred to as the "Wisest fool" because of his contradictory and eccentric policies that had far-reaching consequences for his empire.

Policies and Achievements:
- Shifting of Capital: One of the most significant decisions made by Muhammad Bin Tughlaq was the shifting of his capital from Delhi to Daulatabad (present-day Aurangabad) in the Deccan region. This decision was made to strengthen his control over the southern territories and to counter the Mongol threat. However, the massive logistical challenges and the resistance from the local population led to the failure of this ambitious plan.

- Introduction of Token Currency: Muhammad Bin Tughlaq introduced token currency made of copper and brass to address the shortage of silver coins. However, the sudden introduction and forced acceptance of the token currency caused widespread confusion and economic disruption. People lost faith in the new currency, leading to its failure and a loss of revenue for the state.

- Administrative Reforms: Despite the failures, Muhammad Bin Tughlaq implemented several administrative reforms. He established a separate department for agriculture, introduced a new system of revenue collection based on measurement of land, and tried to improve the efficiency of revenue administration.

- Promotion of Education and Scholarship: The Tughlaq king was known for his patronage of scholars, poets, and artists. He promoted education and established several educational institutions. He also invited scholars from different parts of the world to his court, which helped in the exchange of knowledge and ideas.

Legacy:
Muhammad Bin Tughlaq's reign is often remembered for its failures and eccentric policies, which had a negative impact on the empire. His decisions, such as the capital shift and introduction of token currency, resulted in economic instability and disaffection among the people. However, he also made some positive contributions, particularly in the field of education and administration.

Overall, Muhammad Bin Tughlaq's reign was characterized by a mix of visionary ideas and poor implementation, earning him the epithet of the "Wisest fool." His rule serves as a cautionary tale in governance and highlights the importance of considering practical implications before implementing ambitious policies.