KHELOS DEATHRATTLE SPAM (Cho'Gall edition)

Basically, whatever the situation, if you have The Egg of Khelos, as it's the core of the strategy, never drop it down.

If you have the Shadowsworn Disciple with the Egg of Khelos, here you're cooking lol

Shallow Grave and Dark Pact are the kind of cards you'll have to keep against aggro/midrange decks, as long as you have deathrattles in your mulligan, as it's helping you to survive and giving you tempo.

And, of course, Spiritsinger Umbra is a very powerful bonus if you have The Egg of Khelos. But if you drop it alone, it'll eventually be long to play and not that rewarding, so I'd recommand dropping it.

Basically, the general mulligan advices still apply.
Though, against aggro decks, everything that gives you tempo is good to take.

So, cards like Dark Pact + Any deathrattle will be good as it's giving your HP back without losing anything significant.

Grimoire of Sacrifice is a must against flood aggro decks, as it can clear your opponent's board while not spending anything important.

Twilight Egg in this type of deck can't be ignored as it buffs itself, so against aggro placing big minions fast, it can be a must as your opponent will have to spend an attack to kill it, or accept a threat from your board.

Cards like Unwilling Sacrifice or Chaotic Consumption will eventually be better against mid range decks, but it can be good if your opponent focuses on boosting minions early too.

Basically, the general mulligan advices still apply.

Gigafin is basically here to safe your win condition against control decks. It's not good as a mulligan, but if you know your opponent will have taunts, it can be good to get him at a moment or another. It's probably better not keeping it in a mulligan though.

Same for Glinda Crowskin ; It can be very good to combine with The Egg of Khelos, but is a long term strat that you're most likely not wanting to keep on first turn.

On the other hand, Spiritsinger Umbra is a must against control if you dropped the egg in your mulligan (basically the only way to secure win condition into it), and Unwilling Sacrifice or Chaotic Consumption (which is basically stronger than Unwilling Sacrifice, by the way) can help you clearing a big control board in some situations.