An Equipment that costs one mana and equips to give +1/+1 and haste is already something to consider for a Cube where many of the creatures dont already have haste
This means that while creatures destroyed with removal spells may be copied with Lazav, the same can be done with milled creatures
The backdrop, a flooded room complete with pillars and obelisks , truly harks back to locations such as the Dragons Den from the earlier generations
Shuffle button is great as it can show you what your opening hand might look like.
My trigger would be on the stack before their Bane of Progress trigger could resolve, so would I then put the counters on the Bane of Progress
In terms of the mana curve, if you can reach 5 mana, it's an option to include one or two as a finishing blow, but the drawback is that it doesn't beat 4-mana board wipes