well...i was dueling with horus deck.Then i activate morphing jar eff and send horus LV8 from my hand to grave.Then i use level modulation to bring back horus but my opp. say i cannot because horus cannot be summoned with level modulation unless i summon it before but i always summon horus with discard+lv modulation so is my opp. right?

Your opponent is wrong. Level Modulator states that it can be special summoned from grave disregarding summoning conditions. Not only that, but LM can be used on any level monster as long as its in the grave. There are no special requirements except that it is in the grave.

No Kingwolfy and your opponent is all wrong...Your opponent is right.You must have summoned Horus before you can use it after is sent to grave.If its discarded it does not work like that..here are rulings from netrep

An “LV” monster that normally cannot be Special Summoned except by the
method in its text CANNOT be Special Summoned from the Graveyard with
“Level Modulation” unless it has been previously Special Summoned by
the correct procedure. The “ignore the Summoning conditions” text
allows for these monsters to be Special Summoned only after they have
been properly Summoned by their own effect. This applies to “Horus the
Black Flame Dragon LV8”, “Armed Dragon LV7”, “Silent Swordsman LV7”,
“Silent Magician LV8”, and “Winged Kuriboh LV10”.



All that means Horus must have hit the field before destoyed in order to use the spell card..so your opponent was right

Confirming Kyosuke. Horus can't be special summoned if it was not special summoned successfully.

Yeah. What Kyosuke said it correct.
Thank you for contributing to this section, Kiryu.
I'll lock.

Hm not locked yet.
I'll do it.