Thanks to NeedAName and his latest Magic: the Gathering Challenge I actually noticed there is a magic-the-gathering tag. It was quite some time ago that I played Magic the last time, but nevertheless here is my first Magic: the Gathering puzzle:
The usual magic rules apply here. Please be explicit in mana usage in your solution where relevant.
All permanents in the given setup below are owned by their controllers
Your solution may not assume that an opponent will cooperate with you in some way (e.g. choose no to a may ability that would be bad for you). Your solution must be able to win regardless of any potential choices made by your opponents; it must be able to beat the optimal plays from them.
The oppoent's hand: empty.
The opponent's graveyard: empty.
The opponent has 5 life left.
Your lands: 5 untapped Islands.
Your graveyard: empty.
You have 5 life left.
Win the game in this turn – you won't get another one.