Thundermon

[On Play] [On Deletion] You may return up to 3 Digimon cards with [Mamemon] in their texts from your trash to the top of the deck. Then, delete 1 of your opponent's Digimon with a play cost of 3 or less. For each one this effect returned, add 1 to this effect's play cost maximum.

Inherited effect

[On Deletion] ＜De-Digivolve 1＞ 1 of your opponent's Digimon. (Trash the top card. You can't trash past level 3 cards.)