Because there should be Level 4 Rock Gem-Knights.
Gem-Knight Hematite
*4
EARTH
Rock
ATK 2000
DEF 0
*Generic vanilla mumbo-jumbo*
Gem-Knight Pyrite
*4
EARTH
Rock/Gemini
ATK 1900
DEF 200
Effect: This card is treated as a Normal Monster while face-up on the
field or in the Graveyard. While this card is face-up on the field, you
can Normal Summon it to have it become an Effect Monster with this
effect.
● During your Draw Phase, instead of conducting your normal draw: You
can add 1 Level 4 or lower "Gem-" monster OR 1 "Gem-Knight Fusion" from
your Deck to your hand. This card must be face-up on the field to
activate and to resolve this effect.
Gem-Nautilus
*3
EARTH
Rock/Effect
ATK 200
DEF 100
Effect: During either player's turn: You can discard this card to target
1 "Gem-Knight" monster you control; banish it until your next Standby
Phase.
Alexandrite grabs Hematite, putting itself in the grave for Blocky later while giving you a 2000 vanilla now. Gem-Merchant lets Hema get over big monsters. Nautilus plays Wind-Up Rabbit hand-trap to save your GKs, and as a Level 3, becomes Silvermountain to get back Blocky, Hematite, or Zirconia. Otherwise, you can hang onto it for GK-Fusion. Pyrite is for...Gemini likers.
Gem-Knight Hematite
*4
EARTH
Rock
ATK 2000
DEF 0
*Generic vanilla mumbo-jumbo*
Gem-Knight Pyrite
*4
EARTH
Rock/Gemini
ATK 1900
DEF 200
Effect: This card is treated as a Normal Monster while face-up on the
field or in the Graveyard. While this card is face-up on the field, you
can Normal Summon it to have it become an Effect Monster with this
effect.
● During your Draw Phase, instead of conducting your normal draw: You
can add 1 Level 4 or lower "Gem-" monster OR 1 "Gem-Knight Fusion" from
your Deck to your hand. This card must be face-up on the field to
activate and to resolve this effect.
Gem-Nautilus
*3
EARTH
Rock/Effect
ATK 200
DEF 100
Effect: During either player's turn: You can discard this card to target
1 "Gem-Knight" monster you control; banish it until your next Standby
Phase.
Alexandrite grabs Hematite, putting itself in the grave for Blocky later while giving you a 2000 vanilla now. Gem-Merchant lets Hema get over big monsters. Nautilus plays Wind-Up Rabbit hand-trap to save your GKs, and as a Level 3, becomes Silvermountain to get back Blocky, Hematite, or Zirconia. Otherwise, you can hang onto it for GK-Fusion. Pyrite is for...Gemini likers.