Codexhel;n8448200 said:2. That given equal skill, both players have a roughly 50-50 chance of winning, i.e. uncertainty, which means neither player is sure to win. You may argue that this is simply fairness, but this also means the result of any match will involve some degree of uncertainty. If the result of any given match was certain before you started said match (for example, match fixing and declaring the match result), nobody would watch this or play this. There is little entertainment value for the player, and perhaps none for any observer.
not at all... you're trying to justify your position instead of analyzing factors to reach the conclusion.
just look at league of legends and dota2, the biggest competitive scenes in the world, and all the FPSs that follow them; those games have little to no RNG elements in them, especially if we're talking one instance of dice-roll which can decide the entire match (like a mercenary pulling scorch)
the problem with RNG effects is when they have a large range of outcomes; if the outcome varies from "kinda good" to "kinda bad", it won't be unhealthy for the game. but if the results vary from "win the game" to "lose the game", as it happens with mercenaries pulling scorches, it takes away all the merit of a match. you'll always get the feeling of "he only won/lose because mercenary pulled that scroch", much as it used to happen in hearthstone with cards like piloted shredder and implosion. (i lost count of how many tournament games were carried by a 4-damage implosion...)
if you're going to have RNG elements in a game that relies on consistent strategies, you'll have to limit those RNG results in order to make the game more strategic; otherwise it'll often come down to dice rolls.
saying that the RNG of piloted shredder made it a fair card is simply false; it was one of the most broken cards ever made, and was played in every tempo-oriented deck until the creation of the standard format. there are other deathrattle cards in hearthstone which summon units when they die, and none of them have been as broken as shredder; the main example being infested tauren, a 4-mana 2/3 taunt which summons a 2/2 token.
as for elven mercenary, if pulling a random bronze special from the deck is too powerful, maybe you should take a look at why that effect is more powerful than pulling things like decoy and aeromancy... largely, it comes down the rally effect of clear skies, which in one of the only bronze specials worth running in most decks. indeed, giving elven mercenary an effect that practically reads "play a random bronze unit from your deck" would be too powerful, but that only happens due to rally.
to you use your hearthstone as an example, it would be like piloted shredder summoning a random 2-drop from your deck.
TLDR; instead of having huge RNG variability with elven mercenary, it would be much better to change the rally effect from clear skies.