A highly anticipated card, but does this Digimon deliver?
[BT9-083] Omegamon Merciful Mode has a conditionally-strong digivolving effect, depending on how many [Mega] cards you have slotted beneath him. Under normal circumstances, it would be reasonable to expect 1 to 2 copies hence projecting the scale of his deletion effect.
His deletion effect however, has a perk. Immediately after deletion, he can return 10 cards from the opponent's trash to the bottom of their deck, which nullifies any [On Deletion] effect of deleted Digimons. Another benefit of this effect is that it can cripple some trash-based decks such as Beelstarmon, Beelzemon, hybrid-Susanoomon, and even Mugendramon decks.
His second effect meanwhile, forces Merciful Mode to de-digivolve to trash the top card of the opponent's security. Since Merciful Mode lives and dies by his [When Digivolving] effect, he has little value staying as vanilla LV7 in play therefore reverting to his prior form (either a LV6 or another Omegamon) maybe beneficial.
Note that it is also possible to digivolve Merciful Mode onto a Merciful Mode, to run all his effects twice.