The main TCG mechanic on display in the Emerald/Ruby starter deck is singing
The deck starts with a number of powerful and efficiently costed toxic creates with secondary abilities including Ria Ivor (battle cry, makes mites), Vivisection Evangelist (removal), Nimraiser Paladin (reanimate), Annex Sentry (removal), Porcelain Zealot (buff) and Blightbelly Rat (Proliferate)
The fact that its Blue fits the theme, but it also means youve got access to plenty of spells that will allow you to utilise this to either control the board state, your opponents hands, their library - or basically whatever else you want
*Play Booster box not included *Some assembly required
2019-05-03 If the token's power changes later in the turn after it has attacked, including while Dreadhorde Invasion's second ability is on the stack, it won't cause the token to gain or lose lifelink