AncientMermaimon - Release Special Booster 2.0 (BT18-19)

[On Play] [When Digivolving] Return 1 of your opponent's level 4 or lower Digimon to the hand. For each of your other Digimon, add 1 to the level this effect can choose.
[All Turns] When this Digimon would leave the battle area, from this Digimon's digivolution cards, you may return to the hand or play without paying the cost 1 level 4 or lower blue Digimon card.
[[DigiXros -2] [Lanamon]×[Calmaramon]]