can solemn warning negate the fusion summon?

can explain more?

if im not wrong...fusion gate sets up a condition whereby the player does not have to activate polymerization for a fusion summon. while solemn warning can only negate the activation of a magic, trap, or a monster effect that summons a monster, it cannot negate the effect of a magic or a trap that summons the monster...as compared to royal oppression, where it negates the activation of sp. summoning and card effects that sp. summons...correct me if im wrong plz thx

Solemn Warning


Pay 2000 Life Points. Negate the Summon of a monster OR the activation of a Spell Card, Trap Card, or Effect Monster's effect that includes an effect that Special Summons a monster(s), and destroy that card.


Basically, when you play fusion gate, you're not activating it to special summon. You activate it to paste it onto the field not knowing that you will be special summoning or not.

So when i paste vahalla, my opponent can not solemn warning it? i thought can since it include an effect of sp monster? From what i know is after vahalla is pasted and u use it effect, warning can not be use.