Thunder empire
P4204531

Prism dragon
P4204549

Dragon chief emperor
P4204533

Sun dragon
P4204532

Drei
P4204534

Oni Assasins
P4204529
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Ambush 
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When this face down card is put from
the soul of a card on your field into
your drop zone, you may call it by
paying it's [Call cost] 

Example
Slide1
When the face down card is put from 
the soul of a card on your field into 
your drop zone(not activating
soulguard) and there're 2 or more
cards with [Ambush] ability, player
may choose the sequence of activation.

Slide2

Same goes for if the player activates
Soulguard, you may choose which soul
to be send to drop zone and activates
the ability.
Slide3
Slide4

You may call the monster back from
drop zone.
Slide5

Same goes for face down card with
[Ambush] in the soul of spells and items.
Slide6
Slide7
Slide8