You can substitute this card for any 1 Fusion Material Monster, but the other Fusion Material Monster(s) must be correct. You can Tribute Fusion Material Monsters on the field, including this face-up card; Special Summon 1 corresponding EARTH Fusion Monster from your Extra Deck.
Second effect allows it to special summon earth fusion monster, only if you have the other required material monster.
Needs to be face up when activated, which will give your opponent a chance to destroy it before you can activate it.
Second effect is for EARTH fusion monster only, and there aren't that many available yet.
The strongest EARTH fusion monster that you can summon now is Master of Oz. Summon/set Des Kangaroo and summon Hex next turn to special summon Oz without needing to bring Big Koala.
Hex can also be used to special summon Ryu Senshi since it's not considered fusion summon. If you have Warrior Dai Grepher, summon Hex and activate the ability to get Ryu Senshi out. This isn't doable with Polymerization though.
Tributes for cost / Tributes itself for cost
Fusion Substitute Monster / Special Summons from your Extra Deck
PSA: There's a bug with the AI when auto-dueling. If the AI tries to use this card's effect, it'll crash the app. So until they patch, just pause auto-duel and activate it yourself, then continue auto-duel.
I'd assume this card works rather well with Des Kangaroo. Dunno if it works together with Branch!, though. Haven't been able to test it yet because I don't have either Des Kangaroo or Branch! yet. Can someone confirm or deny?
The sentences in the effect box are not complete.
This card only can subtitute EARTH material monster.
Which means for example you can't polymerization this card + Warrior Dai Grepher to fusion summon Ryu Senshi.
But you can polymerization this card + Spirit Ryu to fusion summon Ryu Senshi.
And i think the second effect of this card, special summon fusion monster by tributing this card & another correct material works the same as the first effect i mentioned above.
Only special summon of an earth monster since from hand ( replace of polimerization) example need summon from hand a master oz put this in your camp, activate your effect and use kangoroo and big koala on this case dont work any substitute...
Second effect: You can Tribute Fusion Material Monsters on the field (not hand), including this face-up card; Special Summon (not fusion summon) 1 corresponding EARTH Fusion Monster from your Extra Deck.
This card is the best fusion material substitute you can get in the game currently because it has a defence of 1600. Enough to survive a turn.
Second effect: Only special summon of an earth monster since from hand ( replace of polimerization) example need summon from hand a master oz put this in your camp, activate your effect and use kangoroo and big koala on this case dont work any substitute...
not to mention that using second effect is count as special summon and not fusion summon. It is not an appropiate fusion summon, so when it destroyed you cannot revive it.