I could not think of a better name, but hey, Goblin suport! [Arcane Goblin Magic]

[Sander]

 

Arcane Goblin Magic
Continuous Spell Card
Each time the battle position of a face-up monster is changed to face-up Defense Position, you can add 1 "Goblin" monster from your Deck to your hand. You can destroy this card; Special Summon as many "Goblin" monsters from your hand as possible.

[Darj]

I think the first effect needs an OPT clause, otherwise you could fill your hand with Goblins through monsters that change their battle positions by themselves (e.g. Ghostricks) and swarm the field in a single turn. For instance, Ghostrick Frost or Pumpkin could be teched in Goblin decks to block a direct attack, and in your turn you flip them face-up manually and then face-down with their effects for a +2 through this Spell.

 

Also, I suggest you remove the "you can" on the first effect to make it mandatory, so the Spell won't miss the timing when other effects activate after a monster changes its battle position (e.g. Shore Knight).

[Mugendramon]

Make it so that it only works when a monster is changed to (face-up?) defense position.

[Sander]

Make it so that it only works when a monster is changed to (face-up?) defense position.

 

Done.