Name an element of the lanthanoid series which is well known to show a +4 oxidation state. Is it a strong oxidizing agent or reducing agent?

Electronic configuration of Ce = [Xe]4f15d16s2
Formation of Ce+4 is favoured by its noble gas configuration, due to which it shows a +4 oxidation state. It can be easily converted into Ce+3, due to which Ce+4 acts as an oxidizing agent.