Sadly, removing Merieke from the battlefield returns the creature to its owner (if its under your control) before it is destroyed, so you wont be able to take advantage of any death triggers this way
Like most Magic: The Gathering cards, the value of Clarion Conqueror depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Tarkir: Dragonstorm)
Punchy early drops like Cactuar, chocobo tokens, Loporrit Scout and Snow Villiers can only dominate until the true bombs start to hit the board
If you have additional combats, each combat step is treated separately, so at end of combat means the combat step that just happened
Tyrant of Kher Ridges ( F, ETB ) - A 4/5 dragon for 5 that deals 4 when it enters