You declare the Type of monster when you activate this card, not when it resolves. This means you pick the Type before the opponent decides whether to chain or not.
You cannot change your mind about the Type after you activate this card. The declared Type remains the same as long as this card is on the field.
This card does not target, so the effects of “Lord of D.” or “Frontier Wiseman” will not protect monsters from this card’s effect.
If the Type of a monster is changed (by the effect of “DNA Surgery” for example) during the turn which it was Summoned, it may attack that turn.