Squirtle, Wartortle and Blastoise

[Níðhöggr]

 

Your opponent cannot target face-up WATER monsters for attacks, except this one. When your opponent attacks this monster, it gains 500 DEF until the end of the Damage Step. During each of your Standby Phases, if "Umi" is face-up on the field, increase this card's DEF by 200.

 

Cannot be Normal Summoned/Set. Must first be Special Summoned (From your hand) by Tributing one face-up "Squirtle" you control. This card can attack while in face-up defense position, and if it does, switch it's ATK and DEF until the end of your opponent's next End Phase. During each of your Standby Phases, if "Umi" is face-up on the field, increase this card's DEF by 200.

 

Cannot be Normal Summoned/Set. Must first be Special summoned (From your hand) by Tributing one face-up "Wartortle" you control. When this card attacks, you can have it gain 1500 ATK until the End Phase, if you do, change it to Defense Position at the end of the Battle Phase. This Position cannot be changed until the End Phase of your next turn. During each of your Standby Phases, if "Umi" is face-up on the field, increase this card's DEF by 200.

 

Cannot be Normal Summoned/Set. Can only be Special Summoned (From your hand or Deck) by Tributing "Blastoise" equipped with "Blastoisinite", and cannot be Special Summoned by other ways. When this card is Special Summoned, it gains DEF equal to the Tributed "Blastoise's" DEF -2500. If this card attacks, it's changed to Defense Position at the end of the Battle Phase, and its Battle Position cannot be changed until the End Phase of your next Turn. As long as "Umi" is face-up on the field, this card can attack directly. You can Tribute a monster; this card gains ATK equal to half the Tributed monster's ATK, until the End Phase.

 

You can only equip this card to a monster if you control a "Key Stone". This card cannot be destroyed by the Effects of Spell, Trap and monster Cards your Opponent controls. If this card would be sent to the Graveyard, banish it instead. 

Key stone here: http://i.imgur.com/rCxAeHi.jpg