Gallis the Star Beast is a level 3 effect monster is not included in the banlist up to March 2012. The design of this card is quite nice, I'll give 7 out of 10.
Gallis the Star Beast is famous of it FTK. a combo which can be done by having 3 specific monster in your hand by using a full fledge monster only deck. It is sure a success if you manage to draw the 3 cards. Such card is of course Gallis the Star Beast, Koa'ki Meiru Doom and Genex Ally Birdman.
Gallis Effect Damage OTK/FTK
Gallis the Star Beast
Koa'ki Meiru Doom
Koa'ki Meiru Boulder
Genex Neutron
Genex Ally Birdman
Giant Rat
Gorz the Emissary of Darkness
Tragoedia
Beast King Barbaros
Battle Fader
Sangan
Cyber Valley
Swift Scarecrow
Fire Ant Ascator
Oracle of the Sun
Cockroach Knight
Sun Dragon Inti
If you have all 3 necessary cards in your hand you can inflict as many damage possible to opponent as long as there is a Cockroach Knight in you deck.
First, Normal Summon Koa'ki Meiru Doom, Then activate Gallis the Star Beast effect to send the top card of your deck to grave, since that this deck consist only monsters, definitely 100% chance of success. 200 damage times the sent monster's level is inflicted and Gallis the Star Beast is special summoned. Afterwards, activate Genex Ally Birdman's effect to return Gallis the Star Beast you control to your hand to special summon it. Genex Ally Birdman is dark monster. Therefore, Koa'ki Meiru Doom will negate its effect and it doesn't special summon it self and remains at your hand. Meanwhile, Gallis the Star Beast is returned to your hand due to the cost to activate Genex Ally Birdman's effect. You can keep activating Gallis the Star Beast and Genex Ally Birdman's effect subsequently to inflict damage to your opponent. Supposedly, the damage is limited to the total level of monsters that remain in you deck, but thanks to Cockroach Knight that is return to the top of your deck each it is sent to grave, you wont be deck out and infinite amount of effect damage ca be inflicted. Note that it is almost the same combo if you include Outstanding Dog Marron instead.
This deck is double edge deck as the OTK cannot be done if opponent has a face-up Skill Drain as your Koa'ki Meiru Doom's effect is negated or if opponent happen to have Fiendish Chain of Forbidden Chalice. Such card can stop this combo from looping and you might be opened for opponent OTK while searching for the 3 cards.
