νικάω I win, am victorious, vanquish, defeat

Easy to remember νικάω, νικῶ. Nike sports equipment makes us victorious, gives us "victory" : ἡ νίκη, τῆς νίκης

Present Indicative
  Contract verbs   Contractions
I win       νικά-ω => νικῶ    ά  + ω  => ῶ
you (sg.) win  
he/she/it wins  		     νικά-εις
    νικά-ει		 => 
=> 		 νικᾷς
νικᾷ 		   ά  + ει  => ᾷ
we win       νικά-ομεν => νικῶμεν    ά  +  ο  => ῶ
you (pl.) win       νικά-ετε => νικᾶte    ά  +  ε  => ᾶ
they win       νικά-ουσιν => νικῶσιν    ά  + ου => ῶ
 
 
Imperative
  Contract verbs   Contractions
eh you, win!      νίκα-ε => νίκᾱ    α  + ε   => ᾱ
(you all) win!        νικά-ετε => νικᾶτε    ά  + ε   => ᾶ
 
 
Infinitive
  Contract verbs   Contractions
to win       νικά-ειν => νικᾶν    ά  + ε   => ᾶ  *
 
 * Note 
This looks like a mistake, but it isn't. It is because the infinitive ending ειν is actually a contraction itself of ε + ε becoming ει.
So we get a double contraction,
first stem νικά + ε + εν
becomes νικά + εν
becomes νικᾶν
The same does happen with -ε contractions, though it looks like there was just one normal contraction of έ + ειν becoming εῖν. For the simple reason that:
πονέ + ε + εν
first becomes πονεί, then + εν becomes πονεῖν