If you get great kicks out of building goofy decks, then by all means throw all these pointers to the wind and have a blast
Post an advertisement on a Facebook group or online and explain that these cards all fit into the Merfolk deck
The Cloak costs three, equips for two, and gives unblockable and shroud to protect it
Here are few things to check out to continue your Magic education: Explore Magic's varying formats, which include standard, modern, vintage, legacy, pauper, commander, and many, many more
Buy commons and uncommons first, then evaluate whether the SRs are necessary for your play context
You can certainly pick off small creatures with just one toughness with Kelsien, but if you want to start taking care of larger creatures, you're going to need to give him deathtouch