Waterdeep

Whenever a non-token creature enters the battlefield under your control put a wealth
counter on Waterdeep.
{t} Remove a wealth counter and add one mana
of any color.
{2}{t} Remove two wealth counters to gain a
treasure token.
{5}{t} Remove three wealth counters to search
your library for a legendary creature card, reveal
it, then shuffle your library and put it on top.