My first lesson as a teacher will be on "Tech Cards." Tech cards typically have no other purpose but to help beat the meta. Tech cards can be found in both the main deck or the side deck. Staple spell and traps are not tech. Sometimes there’s something new that comes about to support the heavily-played Decks that nobody had thought of before. And sometimes you're looking through your old cards and you find a card and smack yourself for not using it before because it's perfect to counter meta.
Examples might include:
Mystical Refpanel (Was used against D. Rulers)
Metaion, the Timelord for those monsters you just can't get over, whether they can't be destroyed by battle or effect.
Thunder King Rai-Oh For just about anything.
The list could go on, but a tech card is dependent on the player, and what he/she thinks can work for what they're up against.
This concludes my first lesson.
