Let's the milling begins!

|Assimibon|???|????|Psychic/Effect|Dark|3||800|400|When this card is attacked; send the top cards of your opponent's Deck to the Graveyard equal to this card's level. If a monster is sent to the graveyard by this effect, this card is not destroyed in that battle. When you take battle damage from the battle involving this card and it is not destroyed: increase its level by 1 and it gains 200 ATK and DEF.|

|Psyche Breaker|???|????|Psychic/Effect|Dark|4||1200|900|If this card attacks or is attacked; You can pay 900 life points; send the top cards of your opponent's Deck to the Graveyard equal to this card's level. If you do: apply the following effects depend on the type(s) of the cards sent to the graveyard by this effect.
- Monster Card: This card gains 200 ATK and DEF.
- Spell Card: Increase this card's Level by 1
- Trap Card: Immediately after this effect resolves, while this card is face-up on the field, the amount of life points to pay its cost is decreased by 100.|

Assimibon: are the cards milled before or after the attack? (Sent to the graveyard this effect = sent to the Graveyard by this effect)

Psyche Breaker mills 4 by battling & paying 900. That might be a bit much for other people, considering it has 4 chances to gain ATK & DEF, increase its level and reduce the effects cost. Plus if you have more than one on the field.

Assimibon mills upon before the attack hits. and i will add "by"

r u saying requiring to battle + paying 900 are too much to just mill 4 cards? if the LP cost need a change, like 600-700?

No, I mean its fine, I was just thinking about it milling equivalent to its own level, which it increases after milling