On guard from some headlines as the summit kicks off Thursday 28 June 2018, and continues on Friday
Immigration issues will likely dominate today, and while not directly relevant to FX and financial markets they are of note in terms of political stability (or not). Merkel has been having some disagreements with her coalition partner, for example.
Friday brings discussion on measures to strengthen euro area policy, which will cover proposals on the European Stability Mechanism (ESM) - perhaps into some sort of European Monetary Fund and a fiscal capacity (so, in addition to monetary policy the EU could enact fiscal stabilization and investment policy). If that ai't enough there is also the issue of banking union.